RRB Group-D Model Paper 16 with answers for online practice

Given:
X is twice as old as Y
Y is 5 times as old as Z
Calculation:
Let the age of X be x, Y be y and Z be z
According to the question,
x = 2y
y = 5z
⇒ x = 10z
According to the question,
z + 5z + 10z = 64
⇒ 16z = 64
⇒ z = 4 years
∴ Age of Y = 5 × 4 = 20 years