Question

Rachel is five years younger than Monica. If the sum of their ages is 21, find the age of each girl.

Answer 1

8 and 13 years old respectively.

Explanation:

Let r = age of Rachael

Let m = age of Monica

M = r + 5 ..........equation 1

r + m = 21 ............equation 2

Substituting equation 1 into equation 2;

r + (r +5) = 21

r + r + 5 = 21

Simplifying the equation, we have;

2r + 5 = 21

2r = 21 - 5

2r = 16

r = 16/2 = 8

To find the value of m;

From equation 1;

m = r + 5

Substituting the value of r;

m = 8 + 5

m = 13.

Therefore, Rachael is 8 years old while Monica is 13.