Question

The present ages of A and B are in the radio of 7:5.The years later, their ages will be in the ratio 9:7.Find their present ages​

Answer 1

Answer:

Step-by-step explanation:

let the present age of a be 7x

and that of b will be 5x

the next year the ratio will change for a to 9x

and for b to 7x

so we have a => 7x+1=9x

b => 5x+1 = 7x

which gives 7x+1/5x+1 = 9x/7x

7x(7x+1) = 9x(5x+1)                  (cross multiply)

(7x)^2 +7x = 45x^2 + 9x

49x^2 + 7x = 45x^2 +9x

49 + 7x = 45 + 9x                  (x^2 will cut x^2)

49-45 = 9x-7x                        (transposition)

4 = 2x

x = 4/2

x = 2

therefore the resent ages of a and b are 7x = 7*2 = 14 and 5x = 5*2 = 10,respectively.