[Question]: Brenda bakes 20 cakes a day. She does this for 9 days and then sells half of the cakes. How many cakes are left with Brenda?
[Answer]: After 9 days, Brenda bakes 20 * 9 = 180 cakes. After she sells half of them, the remaining will be 180 / 2 = 90 cakes.
So the answer is 90.

[Question]: Jaydee can type 38 words in a minute. How many hours will he take to finish typing a research paper with 4560 words?
[Answer]: Jaydee can type his research paper in 4560 / 38 = 120 minutes. Since there are 60 minutes in an hour, he can finish it in 120 / 60 = 2 hours.
So the answer is 2.

[Question]: Preston has a sandwich shop. He charges $5 for each sandwich. He also charges $20 for a delivery fee. Abra Company orders 18 sandwiches from Preston and also tips him 10%. How much total, in dollars, did Preston receive?
[Answer]:
First, find the price of the sandwiches $5 per sandwich * 18 sandwiches = $90. Now add in the delivery fee $90 + $20 = $110. Now the tip $110 * 0.10 = $11. Add the tip to the price of the sandwiches $110 + $11 = $121 in total.
So the answer is 121.