How do you solve x - 9y = -80 and 2y - 2x = 16 using substitution?
1 Answer
May 27, 2018
Explanation:
x-9y=-80to(1)
2y-2x=16to(2)
"rearrange equation "(1)" expressing x in terms of y"
x=-80+9yto(3)
color(blue)"substitute "x=-80+9y" in equation "(2)
2y-2(-80+9y)=16
2y+160-18y=16
-16y+160=16
"subtract 160 from both sides"
-16y=16-160=-144
"divide both sides by "-16
y=(-144)/(-16)=9
"substitute "y=9" in equation "(3)
x=-80+81=1
"solution is "(x,y)to(1,9)
graph{(y-1/9x-80/9)(y-x-8)=0 [-20, 20, -10, 10]}
