Question:The sum of the ages of Aruna and her mother is 49 years. Also, 7 years ago, the mother's age was 4 times Aruna's age. Find the present age of Aruna's mother. 

Let Aruna's age 7 years ago be x.

 Mother's age 7 years ago = 4x

`:.` (x + 7) + (4x + 7) = 49

 or x =7

`:.` Mother's present age = (4x +7) = (4 x 7 +7) =35 years

Question:The ages of A and B differ by 16 years. If 6 years ago, the elder one be 3 times as old as the younger one, find their present ages. 

Let A's age = x & B's age = (x + 16)
3 (x - 6) = (x + 16 -6) 
or x = 7

`:.` Mother's present age = (4x + 7) = 35 years.