Question. Betty and Dora started making some cupcakes at the same time. Betty makes 10 cupcakes every hour and Dora makes 8 every hour. If Betty took a two-hour break, what is the difference between the number of cupcakes they made after 5 hours?
Answer. 10
What step-by-step reasoning justifies that answer?
Reasoning: Dora made 8 cupcakes per hour for 5 hours for a total of 8 * 5 = 40 cupcakes. Betty took a 2 - hour break so she spent 5 - 2 = 3 hours making cupcakes. Betty made 10 cupcakes per hour for 3 hours for a total of 10 * 3 = 30 cupcakes. The difference between the number of cupcakes they made is 40 - 30 = 10 cupcakes.