Question

The difference between the ages of two cousins is 10 years.15 years ago if the elder one was twice as old as the younger one,find their present ages.

Answer 1

at present
age of older one = x
age of younger= x-10

15 years ago their ages

older one = x-15

younger =x-10-15= x-25

age of elder = 2× younger

x-15 = 2 (x-25)

x-15= 2x -50

-15+50=2x-x
35 =x

x=35

therefore

now elder age = x =35yr

younger age = x-10

=35-10 =25

Answer 2

Cousin 1 – x.

Cousin 2 – y.

The difference between the ages of two cousins is 10 years:

− = 10

15 years ago, if the elder one was twice as old as the younger one:

− 15 = 2( − 15)

So, we obtain the system of two equations:

− = 10

− 15 = 2( − 15) →

10 + − 15 = 2( − 15) → = 25 → = 35

Answer.

Cousins present ages are 25 and 35 year