The sum of the ages of the father and son is 44 years. After 8 years, the age of the father will be twice the age of the son. Find their present ages.

Soln:
Let the present age of father = x years
and the present age of son = y years
according to the first condition 
x + y =44 ........(i)
according to the second condition
x+8 = 2(y+8)
or x+ 8 = 2y + 16
or x- 2y = 8 ............(ii)
solve the equation (i) & (ii) we get
x + y =44
x- 2y = 8
••••••••••••••••••••••••
3y = 36
or y = 12
put the value of y in equation (i), we get
x + 12 =44
or x = 32
so the present age of father = x =32 years
and the present age of son = y = 12 years.