Question 683583
Let the boy's age bex
girls age be y

2 years ago their ages
x-2 boy's age
y-2 girls age

(x-2)+(y-2)=20
x+y-4=20
x+y=16...................(1)

3 years hence

their ages will be 
x+3 & y+3

(x+3)-(y+3)=10
x-y=10.................(2)

Add (1) & (2)

2x= 26
x= 13 the boy's age
Girls age = 20-13=7

Their ages could be 13 & 7