The average age of A, B, C and D is 40 years. The present age of B is 90% of the present age of A and the present age of D is 40% of the present age of C. If 10 years hence the age of B is 24 years less than the age of C at that time, then find the sum of the present ages of B and D?
A. 50 years
B. 40 years
C. 70 years
D. 60 years
E. 90 years
Sol:
A + B + C + D = 40 * 4 = 160
B = 90/100 * A
B/A = 9/10
Let B = 9k, A = 10k
D = 40/100 * C
D/C = 2/5
C – B = 24
C = 24 + 9k
D = 2/5 * (24 + 9k)
9k + 10k + 24 + 9k + 48/5 + 18k/5 = 160
k = 4
Present age of B = 9 * 4 = 36
Present age of D = 2/5 * (24 + 36) = 24
Sum of the ages of B and D = 36 + 24 = 60 years
