She earned $10.00.

(Working backward)

**Step 1:** Begin with the amount they had left: $2.74.

**Step 2: **Find out how much they spent.

**Step 3:** Add the amount spent to the amount they had left.

**Step 4:** Subtract the cost of the exercise wheel they returned.

$20.69

__ – 5.69__

$15.00 amount brought to the store

**Step 5:** Subtract the amount of money Lee contributed.

$15.00

__ – 5.00__

$10.00

Nicki had earned $10 last week.