The sum of the ages of three sisters is 64.

Question

The sum of the ages of three sisters is 64. The age of the oldest is twice the age of the youngest. The ages of the two older sisters is a difference of six years. what is the age of the younges sister?

 

Answer 1

Hello Ingrid

 

Let a = the oldest sister, b = the middle and c = the youngest.

 

Eq 1) a + b + c = 64

 

Eq 2) a = 2c

 

Eq 3) a - b = 6

 

Substitute Eq 2) into Eq 3) and rearrange to solve for b

 

2c - b = 6

b = 2c - 6.. Substitute this equation and Eq 2) in Eq 1)

 

2c + 2c - 6 + c = 64

 

5c = 70

 

c = 70 / 5 = 14

 

Youngest sister is 14 years old.