Question

the ratio of ages A and B seven years ago was 3:4 respectively. the ratio of their ages nine years from now will 7:8. whats is b age at present​

Answer 1

Answer:

Let x and y be the present ages of A and B respectively.

Then according to what is given,(x-7)/(y-7)=3/4 and (x+9)/(y+9)=7/8

On simplifying we get, 4x-3y = 7 ....(1) and 8x-7y = -9 ....(2)

Multiplying (1) by 2,we get 8x-6y = 14 ....(3)

Now subtracting 2 from 3 we get -6y+7y=23.

y=23 which is the present age of B

Step-by-step explanation:

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Answer 2

let age of A and B be X and y

seven years ago their ages were x-7,y-7

the ratio is x-7/y-7=3/4

4(x-7)=3(y-7)

4x-28=3y-21

4x-3y-7=0.......(1)

Nine years from now their ages will be X+9 and y+9.

ratio of ages is 7:8

X+9/y+9=7/8

8x+72=7y+63

8x-7y+9=0..............(2)

multiply equation (1) with 2

8x-6y-14=0......(3)

(3)-(2)

8x-6y-14-8x+7y-9=0

y=14+9=23

age of b=y=23