Question

Three sisters have ages that are consecutive odd integers. The sum of their ages is 57. Find the age of each sister. You must include your work for full credit.

Answer 1

17, 19 and 21

Explanation:

Consecutive odd numbers mean odd numbers that are right next to each other.

Eg: 3, 5, 7

Let x represent the youngest sister. The sister older than her will be 2 years older than her, hence (2 + x). The oldest sister would be 4 years older than the youngest and two years older than the middle sister, hence (4 + x).

The sum of their age = 57.

Hence:

x + (2 + x) + (4 + x) = 57

x + 2 + x + 4 + x = 57

Simplify

3x + 6 = 57

Rearrange

3x = 57 - 6

3x = 51

Divide both sides by 3 to make x on its own (this way we can find the age of the youngest sister).

x = 17 (youngest sister is 17 years old)

x + 2 = 19 (middle sister is 19 years old)

x + 4 = 21 (oldest sister is 21 years old)