SChand Composite Mathematics Class 7 Chapter 7 Linear Equation with one Variable Exercise 7B

 Exercise  7 B 

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Q1 | Ex-7B | Class 7 | SChand Composite Maths | Linear Equation with one Variable | myhelper

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Question 1

The sum of Ritu  age and Ashu age is 25. Ritu is 12 years old . Write an equation to find ashu age ?

 

Sol: Let Ritu age =x ; Ashu age = y

Acc. to question = x+y=25 

= $12+y=25 \Rightarrow y=25-12=13$

Ashu age = 13 year

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Question 2

A number decreased by 4 is equal to -6 . find the number

Sol: Let  the number =x 

Acc. to question x-4=-6

$\Rightarrow x=-6+4 \Rightarrow x=-2$

The number =- 2 Ans

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Question 3

7 times a number decreased by 3 equal to 18. find the number 

Sol : 

Let the number= x 

$\Rightarrow 7 \times x-3=18$

$\Rightarrow 7 x=18+3$

$\Rightarrow 7 \times x=21$

$\Rightarrow x=\frac{21}{7} \Rightarrow x=3$

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Question 4

One- fifth of a number is 9. find the number 

Sol : 

Let the number =x 

Acc. to question = $\frac{1}{5} \times x=9$ 

$x=9 \times 5 \quad \Rightarrow x=45$

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Question 5

How old is ramesh if 10 year ago he was 25 year old ? 

Sol :

 Age of ramesh 10 year ago = 25 year 

∵ Age of ramesh , after 10 year = 25 + 10 = 35 year 

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Question 6

Apporv received three-fourths of all votes cast in the election far school president. If he received 876 votes, how many student voted ?

Sol : 

Apoorv received votes = 876 

Let total number of votes = x 

Acc. to question = $\frac{3}{4} \times x=876$ 

x= $876 \times \frac{4}{3}=1168$

Total No, of votes = 1168 votes of students 

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Question 7

After gaining 15 kg , Nisha weight 60 kg . What was her previous weight ? 

Sol: Let the previous weight of Nisha = x 

Weight gained = 15kg 

x+ 15 =60 = x= 60 -15 =45kg 

Previous weight = 45kg answer 

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Question 8

A pole x meters long is broken into two parts, One part is 5 meters long. 

(i) What is the length of the other parts? 

(ii) If the other part is 6 meters long. write an equation and use it to find the value of x 

Sol: (i) Length of pole = x m 

other part = (x-5) m answer 

(ii) If the other part = x-5 

Acc , to Question = x -5 = 6 

=x=6+5 = 11m 

Length of pole = 11m answer

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Question 9

The teacher tells the class that the highest marks obtained by a student in her class in three times the lowest marks minus seven . If the highest marks are 86 , find the lowest marks. 

Sol: Let the lowest marks = x 

Acc. to question= $3 x-7=86 \Rightarrow 3 x=86+7 .$

$3 x=93 \Rightarrow x=\frac{93}{3}=31$

∵ Lowest marks = 31 

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Question 10

Benny thinks of a number subtracts 18 from it and divides the difference by 3. The result is -4 . what is the number ? 

Sol: Let the number =x 

$\frac{x-18}{3}=-4 \Rightarrow x-18=-4 \times 3$

$\Rightarrow \quad x-18=-12 \quad x=-12+18$

$\Rightarrow \quad x=6 \quad$ Numbcr $=6$ answer 

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Question 11

Mr. Grover is three times as old as his son and the sum of their age is 48 . How old is each ?

Sol: Let the age of son = x 

Age of Mr. Grover= 3x 

$\Rightarrow \quad 3 x+x=48 \Rightarrow 4 x=48 .$

$\Rightarrow \quad x=\frac{48}{4}=12$ years $\therefore$ Son age = 12 years answer

= Mr. Grover age $=3 \times 12=36$ years

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Question 12

Sunil is 48 years old . He is 7 years less than 5 times his daughter's age . What is his daughter's age ? 

Sol: Let daughter age =x 

$\Rightarrow 5 x-7=48 \Rightarrow 5 x=48+7 \Rightarrow 5 x=55$

$\Rightarrow x=\frac{55}{5} \Rightarrow x=11$ years 

daughter's age = 11 y answer 

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Question 13

A number is 6 more than two times another number. The sum of  tthe two number is 24. Find the number 

Sol: Let one number =x ; Other = y = 2x +6

$x+y=24 \Rightarrow x+2 x+6=24$

$3 x=24-6 \quad \Rightarrow \quad 3 x=18 \quad \Rightarrow x=\frac{18}{3}=6$

x =6 ; y = 2x +6 = $2 \times 6+6=12+6=18$

y = 18 answer 

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Question 14

Four times Sonu age decrease by 3 is equal to 3 times his age increased by 7. How old is sonu? 

Sol : 

Sonu age =x 

$\Rightarrow 4 x-3=3 x+7$

$\Rightarrow 4 x-3 x=7+3$

$\Rightarrow x=10$ years

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Question 15

Find the 3 Consecutive number whose sum is 81

Sol : 

Number are x, x+1 , x+2

$x+x+1+x+2=81$

3x+3=81

$3 x=81-3$

$3 x=78 \Rightarrow x=\frac{78}{3}$

x=26

x +1 = 26+ 1 = 27

x+2 =26+ 2 = 28 answer