Answer:
Cheryl's age = x = 7 years
Rita's age = y = 17 years
Explanation:
Let
Cheryl's age = x
Rita's age = y
Two years ago, Rita was three times older than Cheryl
(y - 2) = 3(x - 2)
y - 2 = 3x - 6
y = 3x - 6 + 2
= 3x - 4
y = 3x - 4
In 3 years, Rita will be twice older than Cheryl
(y + 3) = 2(x + 3)
y + 3 = 2x + 6
y = 2x + 6 - 3
= 2x + 3
y = 2x + 3
Equate both equations
3x - 4 = 2x + 3
Collect like terms
3x - 2x = 3 + 4
x = 7 years
Substitute x = 7 into
y = 2x + 3
= 2(7) + 3
= 14 + 3
= 17
y = 17 years
Cheryl's age = x = 7 years
Rita's age = y = 17 years