Question

The ratio between the ages of raju and ravi is 9:7 and sum of their ages at present is 48yrs. What will be ratio b/w their ages aftr 15 years?

Answer 1

ratio=9:7
9x+7x=48
16x=48
x=48\16
x=3
so the ages are 
9*3 and 7*3 which is 27 and 21 respectively
after 15 years the ratio shall be
27+15 and 21+15 which is
42 and 36 respectively..
the ratio therefore 
=42\36
=7:6  ANS

Answer 2

given :-
x/y=9/7
7x=9y
7x- 9y =0...(1)
and , x+y= 48....(2)
multiplying (2) by 7 & substracting it from (1).

7x-9y - 7x - 7y = 0-48×7
-16y = -336
y = 21
x+21 = 48
x = 27

after 15 year x = 27+15= 42
y = 21+15=36

x/y = 42/36
=7/6