# NCERT Solution for Class 8  Maths Chapter – 2   Exercise 2.4

Q1. Amina thinks of a number and subtracts 5/2 from it. She multiplies the result by 8. The result now obtained is 3 times the same number she thought of . What is the number?

Solution:-

( x – 5/2 ) x 8 = 3x

8x – 40/2 = 3x

8x – 3x = 40/2

5x = 20

X = 4

Q2. A positive number is 5 times another number. If 21 is added to both the numbers, then one of the new number. What are the numbers?

Solution:-

5x + 21 = 2( x + 21)

5x +

21 = 2x + 42

5x – 2x = 42 – 21

3x = 21

X = 7

One number = x = 7

Other number = 5x = 5 x 7 = 35

Q3. Sum of the digits of a two – digit number is 9. When we interchange the digits, it is found that the resulting new number is greater than the original number by 27, What is the two – digit number?

Solution:-

10x + ( 9 – x ) +27 = 10( 9 – x ) + x

10x + 9 – x + 27 = 90 – 10x + x

9x + 36 = 90 – 9x

9x + 9x = 90-36

18x = 54

X = 3

The number is 36.

Q4. One of the two digits of a two – digit number is three times the other digit. If you interchange the digits numbers and add the resulting number to the original number, you get 88. What is the original number ?

Solution:-

( 30x + x) + ( 10x + 3x ) = 88

31x + 13x = 88

44x = 88

X = 2

The number is 26.

Q5. Shobo mother present age is six times shobo present age. Shobo age five years from now will be one third of his mothers present age . What are their present age?

Solution:-

(x+ 5) = (1/3) x 6x

X + 5 = 2x

2x – x = 5

X = 5

Present age of shobo mother is  = 6x = 6×5 = 30 years.

# Aman age = 3x = 3 x 20 = 60 years

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NCERT Solution for Class 8  Maths Chapter – 2   Exercise 2.4 Q1. Amina thinks of a number and subtracts 5/2 from…