The sum of the ages of Dorothy and Dona is 41. In five years, Dorothy will be twice as old as Dona. Find their ages 3 years ago.

To solve this problem, let's break it down step by step:

Step 1: Set up the equations:
Let's assume the current age of Dorothy is D, and the current age of Dona is D.
We are given two pieces of information:
1) The sum of their ages is 41: D + D = 41.
2) In five years, Dorothy will be twice as old as Dona: (D + 5) = 2(D + 5).

Step 2: Solve the equations:
From the first equation, we have: D + D = 41, which simplifies to 2D = 41.
Divide both sides by 2 to solve for D: D = 41/2, which simplifies to D = 20.5.

Step 3: Find their ages 3 years ago:
To find their ages 3 years ago, subtract 3 from their current ages.
For Dorothy: D - 3 = 20.5 - 3 = 17.5.
For Dona: D - 3 = 20.5 - 3 = 17.5.

So, their ages 3 years ago were 17.5.