The answer should be -3, I can explain it if you want.
The (3, 1/5) would be a solution while the (-1,1) wouldn’t because when you write this equation in the slope intercept form which is y = 3/5x - 8/5
1/5 = 3/5 (3) - 8/5
would end up with 1/5 = 1/5 which is write
While,
1 = 3/5 (-1) - 8/5
Would end up with
1 = 11/5 which is wrong
ABCD is a square and a quadrilateral
Hey!
First, let's write the problem.

Multiply

with

.

Subtract

from both sides.


Divide both sides by

.


Let me know if you have any questions regarding this problem!
Thanks!
-TetraFish