SOLUTION: solve by the substitution method. 7x+4y= -1 -5x+y=20

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Question 491115: solve by the substitution method.
7x+4y= -1
-5x+y=20
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
7 x + 4 y = -1 .............1
1 y = 20 + 5 x ---------2
/ 1 =
y = 20 + 5 x
Substitute y in (1)
7 x + 4 ( 20 + 5 x ) = -1
7 x + 80 + 20 x = -1
7 x + 20 x = -1 -80
27 x = -81
/ 27
x= -3
Plug the value of x in (1)
7 x + 4 y = -1
7 * -3 + 4 y = -1
-21 + 4 y = -1
4 y = 20
/ 4
y= 5
m.ananth@hotmail.ca