Four friends will build a model castle. The castle will have 4 walls made of 20 blocks each and 4 towers made of 5 blocks each. Each friend described a way
to find the total number of blocks needed to build the castle, as shown below.
• Gordon: “Add 20 and 5, and then multiply that sum by 4."
• Kate: "Add 4 and 5, and then multiply that sum by 20."
• Selena: "Multiply 4 and 5. Multiply 4 and 20. Then add those 2 products
together."
• Thomas: "Add 20, 4, and 5, and then multiply that sum by 4."
Which 2 friends wrote correct expressions?