SOLUTION: I have these 2 equations and there y slope intercept which are 2x+2y=140 y=-x+70 1x-1y=20 y=x-20 The answer for x and y are shown as x is 45 and y is 25(both positiv

Algebra ->  Linear-equations -> SOLUTION: I have these 2 equations and there y slope intercept which are 2x+2y=140 y=-x+70 1x-1y=20 y=x-20 The answer for x and y are shown as x is 45 and y is 25(both positiv      Log On


   

Question 197307: I have these 2 equations and there y slope intercept which are
2x+2y=140 y=-x+70
1x-1y=20 y=x-20
The answer for x and y are shown as x is 45 and y is 25(both positive #'s)
I need it explained to me how the 45 and 25 are figured out.
Thanks!
Answer by RAY100(1637) About Me  (Show Source):
You can put this solution on YOUR website!
Problem #1
.
(1) 2x +2y = 140
(2) x-y =20
.
Your start was good,,(1) becomes y=-x+70,,,and (2) becomes y = x-20
.
Setting these equal to each other, substitution,
.
-x+70 = x-20
.
90 = 2x
.
x=45,,,answer
.
Subst into (2) ,,,45 -y = 20,,,y=45-20,,,,y = 25
.
checking
in (1) 2(45) + 2(25) = 140,,,140 =140,,,ok
in (2) (45) - (25) = 20,,,20 = 20,,,ok