What is the measure of DEF? Pls help me asap

Another type of subtraction equation is 16-b=7. explain how you would sole this equation then solve it.

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 ?

How many square centimeters of wrapping paper will be used to wrap the shoe box?