A’s present age is equal to 20% of his father's age 15 years ago and B’s present age is 60% of his father’s age ten years ago. If the sum of A’s present age and B’s present age is 31, then find their fathers present age? (A and B are brothers)
Answer & Solution
Correct option is B
Let present age of father = F
Let present age of A = a Let present age of B = b
Given: A = 20% of father’s age 15 years ago
So, a = 0.2(F - 15) ...(1)
B = 60% of father’s age 10 years ago
So, b = 0.6(F - 10) ...(2)
Now, a + b = 31
Substitute (1) and (2):
0.2(F - 15) + 0.6(F - 10) = 31
0.2F - 3 + 0.6F - 6 = 31
0.8F - 9 = 31
0.8F = 40
F = 50
Exam Hall Method:









