Please help me please I reallly need help

Acollege is planning to construct a rectangular parking lot on land bordered on one side by a highway. the plan is to use 680 feet of fencing to fence off the other three sides. what dimensions should the lot have if the enclosed area is to be a maximum?

You paint a 1/2 of a wall in 1/4 hour. how long will it take you to paint one wall

How is this equation completed? i cannot find any examples in the book.