Question 379914
For 1) and 2) just set up an equation in terms of some width w. For 1) suppose the width is w and the length is 4w. Since the perimeter of the rectangle is 150 feet, we have 2(w + 4w) = 150 --> 10w = 150 --> w = 15. The width is 15 and the length is 60.

Part 2) is very similar to the first one, I'll leave that to you to do. :)

Part 3) cannot be solved. There are infinitely many rectangles with perimeter 40.