Final answer:
Lizzie and Maggie left a $5.10 tip for the waiter by calculating 20% of their $25.50 dinner cost.
Step-by-step explanation:
To calculate how much money Lizzie and Maggie left for the tip, we need to find 20% of the dinner cost, which was $25.50. To find the tip amount, convert the percentage to a decimal by dividing by 100 (20% = 0.20) and then multiply by the cost of the meal.
Tip amount = 0.20 × $25.50
Tip amount = $5.10
Therefore, Lizzie and Maggie left a $5.10 tip for the waiter.