Question

Mary is twice older than her sister. In 5 years time, she will be 2 years older than her sister. Find how old are they both now

Answer 1

Let the mary's sister's age be x 
Now , mary's age = 2x
Given that in 5 years time mary's age is x+2 
⇒ x + 2 + 5 = 2x +5 
⇒ x + 7 = 2x + 5 
⇒2x - x = 7 - 5 
⇒ x = 2 
Therefore , Mary's age = 2x = 2 × 2 = 4 
Mary's sister's age = x = 2 .

Answer 2

Answer:

let

sister=a

mary=2a

in 5 years time

sister=x+5

mary=2a+5

in 5 years time Mary is 2 years older than her sister

2a+5=(a+5)+2

solve a

2a+5=(a+5)+2

2a+5=a+5+2

2a+5=a+7

a=2

AGES

sister =a=2

mary=2a =2(2)=4