let

m = the present age of Abu's mother

a = the present age of Abu

The present age of Abu’s mother is three times the present age of him:

m = 3a

After 5 years their ages will add to 66 years:

m + 5 + a + 5 = 66

m + a + 10 = 66 subtract 10 from both sides

m + a = 56

by solving the system of equations

m = 3a

m + a = 56

we find

m = 42 years

a = 14 years

click here to see the step by step solution of the system of equations

Abu's mother present age is 42 years.

Abus present age is 14 years.