Question

Banu is 20 years older than Binu. In 5 years, Banu will be twice as old as Binu. Find their present ages.

Answer 1

Let Banu's age=a; Binu's age =i
As per conditions,
a=i+20;

a+5=2(i+5)
or,i+20+5=2i+10
or,i+25=2i+10
or,2i-i=25-10
or,i=15

Therefore a=20+15
or, a=35

Banu's age=35 years
Binu's age =15 years

Answer 2

let banu age be x there4 
binu age =y 
there4 x=y+20
in 5 yrs.
ba age =x+5
bi age =y+5
according to ques,
x+5=2(y+5)
solving 
y=15 and x=35