Question

the difference between two cousins are 10 years. 15 years ago if elder ones are twice as the younger once find their present age.

Answer 1

let's assume elder's age = x
................. younger's age = y

x - y = 10
therefore, x = 10 + y. .... equation 1

x - 15 = 2 (y-15). .......... equation 2

apply equation 1 in 2
y-5 = 2y - 30
y = 25
therefore x = 35