Currently
Let Amy's current age be x. Since Dianne is 23 years older than her daughter, then she is (x + 23) years old.
In 5 years
Amy's age will be (x + 5) years.
Dianne's age will be:

The sum of their ages in 5 years is 91. Therefore, we have:

Solving, we have:

Amy is 29 years old. Therefore, Dianne will be:

ANSWER:
Amy is 29 years old, and Dianne is 52 years old.