Pls me with 4, 5, and 6! (show work! ) + lots of

Translate the word phrase into a math expression. 15 fewer than the product of 4 and a number. (pls immediately)

What properties allow transformation to be used as a problem solving tool

Acyclist bike x distance at 10 miles per hour .and returns over the same path at 8 miles per hour. what is the cyclist average rate for the round trip in miles per hour ?