If the garden is square, then the perimeter would be 90. 15(2)+30(2)=90
810/90=9
So it would cost $9 per foot.
To find the slope, you use the slope formula (m):
and plug in the two points
(-3, 4) = (x₁, y₁)
(2, -1) = (x₂, y₂)
[two negatives cancel each other out and become positive]
m = -1 The slope is -1