Question 30518
Ann's present age exceeds Bob's age by 25 years. In 15 years Ann will be twice as old as bob.Find both ages 
Ann now-
Bob now-
Ann in 15-
Bob in 15- 

Let Ann be A yrs old now
and let Bob be B yrs old now
Ann's present age exceeds Bob's age by 25 years 
That is A = B+25 ----(1)
In 15 years Ann will be twice as old as bob.
In 15 years 
Ann will be  (A+15) yrs old
and Bob will be  (B+15) yrs old
And then Ann will be twice as old as bob.
Therefore (A+15)= 2(B+15)
A+15 = 2B +30
A-2B = 30-15
A-2B = 15 ----(2)
Using (1), that is A = B+25 
(B+25)-2B = 15
(B-2B) = 15-25 
-B = -10
Therefore B = 10
Putting B = 10 in (1)
A = B+25 = 10+25 = 35

Answer: Ann's present age is 35 yrs
and Bob's present age is 10 yrs
In 15 yrs
Ann  will be (35+15) = 50 yrs
and Bob will be (10+15) = 25 yrs
Verification: In 15 years Ann should be twice as old as bob 
which is of course true as 50 is twice 25.