The ratio of ages of father and son is 5:2. After 10 years, ratio will become 7:3. Find father’s age.

A. 35
B. 40
C. 45
D. 50

Solution:
Let ages = 5x, 2x
After 10 yrs → (5x+10)/(2x+10) = 7/3
Cross multiply → 15x+30 = 14x+70 → x=40
Father = 5x= 50
Answer: D