I'm having difficulty with these two problems. I have the answers in front of me, but I don't know how to come to them on my own.

1. Use the letter d and the number 10 as required to write an expression that tells the number of 3-cent stamps that can be purchased for d dollars.

2. A truck went a distance of d miles in m minutes and arrived 1 hour late. How fast should the truck have been driven to have arrived on time?

Thank you. Please explain how you come to your answer.