I need help, trying to find slope and y intercept

the slope is -1 over 4

y intercept is (0,-8)                

Step-by-step explanation:

Wow !  We might actually have to do some work for this one.

First, you have to find the area of the rectangle.  I guess, just now,
that means the one who has to do that is me.

We know that it's a rectangle, because they told us so.
The corners are located at
  (1, 4)
  (4, 7)
  (8, 3)
and
  (5, 0).

Do you remember how to find the distance between 2 points ?

               Distance  =  √ (difference-in-'x' ²  +  difference-in-'y' ²)

The distance between the first 2 points is    √(3² + 3²)  =  √18

The distance between point-2 and point-3 is  √(4² + 4²) = √32

The distance between point-3 and point-4 is  √(3² + 3²) = √18

The distance between point-4 and point-1 is  √(4² + 4²) = √32 .

Notice that it wasn't really necessary to find all four distances.   
As soon as I found the first two distances, I knew that one is the length
of the rectangle and the other one is the width of the rectangle, so I didn't
have to bother finding the other two, because I knew that they would be
the same as the first two.  I just did it anyway, to make SURE that they
were the same.  That helped me be sure that I didn't make any mistakes.

So here we are, outstanding in our field. (Actually, in Ms. Stone's field.)
We have a rectangle with a length of √32 units and a width of √18 units.

The area of any rectangle is  (length) · (width)

                                       =  (√32 units) · (√18 units)

                                       =  √(32 · 18)    units²

                                       =   √ (576)      units²

                                       =        24  units²   .

We also know that each square unit on the map indicates 16 acres.
So the actual area of the field is

                      (24 units²) · (16 acres/unit²)  =  384 acres .

Ms. Stone sold the field for  $858,240 .

The unit sale price was

                ($858,240) / (384 acres)  =  $2,235 / acre .

Ms. Stone can now move into the city and live the life of a rich lady.