Answer:
x^2 − 20x + 100
Step-by-step explanation:
y=15
x=43
(any variable can be used, I used x and y to make it easier to show)
x+y=58
x-y=28
get x by its self
x=58-y
then subsitute into the other equation
(58-y)-y=28
58-2y=28
-2y=-30
sub. again
x+15=58
Answer: c = -5, -8
c^2 +13c+40=0
(c+5)(c+8)=40
c = -5, -8
