Suppose you are building a rectangular pen for your goats. you use 400 feet of fencing for the pen.

Part A

The pen has a rectangular shape of length l and width, say w.

The perimeter (the fencing) of this rectangle is 2l+2w, as in the rectangle we have 2 opposing sides of length l and 2 opposing sides of length w.

This means that 2l+2w=400

subtract 2l from both sides:

2w=400-2l

divide by 2:

w=200-l, so we find that the width is 200-l.

part B

we are asked to find w when l=80 ft,

since we have w=200-l, we can find w for l=80 ft by substituting :

w=200-l=200-80=120  (feet)

Part C

The area of the pen when l=90 feet is:

 (square feet)

Abit confused about what you mean, but i think you might be referring to slope intercept form: y = mx + bin that case b, or the y intercept is already given.(0,-1)find the slope by using the formulay2 - y1/x2 - x1the final slope will be 4/2, equivalent to 2.now your equation should look like thisy = 4/2x -1sorry if this didn’t you out!