SOLUTION: I'm not sure what to do here... Can I get some help? Solve using the substitution method. 5x - 3y = 8, -5x + y = 4

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Question 579132: I'm not sure what to do here... Can I get some help?

Solve using the substitution method.
5x - 3y = 8, -5x + y = 4

Found 2 solutions by mananth, josmiceli:
Answer by mananth(16946) About Me  (Show Source):
You can put this solution on YOUR website!
-5x+y=4 .............1
y=4+5x

5x-3y=8
Substitute y in (2)
5x-3(4+5x)=8
5 x + -12 -15 x = 8
5 x -15 x = 20
-10 x = 20
/ -10
x= -2
Plug the value of x in (1)
-5x+y=4
-5*-2+y =4
10+y=4
y = -6

m.ananth@hotmail.ca

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
(1) +5x+-+3y+=+8+
(2) +-5x+%2B+y+=+4+
To do substitution, take one of the equations
and isolate either x or y on one side
-----------------
Add +5x+ to both sides of (2)
(2) +y+=+5x+%2B+4+
Now substitute this value of y for
the y in equation (1)
(1) +5x+-+3%2A%285x+%2B+4+%29+=+8+
(1) +5x+-+15x+-+12+=+8+
Add 12 to both sides
(1) +-10x+=+12+%2B+8+
(1) +-10x+=+20+
Divide both sides by -10
(1) +x+=+-2+
Now substitute this value for x back
into either (1) or (2)
(1) +5%2A%28-2%29+-+3y+=+8+
(1) +-10+-+3y+=+8+
Add 10 to both sides
(1) +-3y+=+18+
Divide both sides by -3
(1) +y+=+-6+
check answers:
(2) +-5x+%2B+y+=+4+
(2) +-5%2A%28-2%29+%2B+%28-6%29+=+4+
(2) +10+-+6+=+4+
(2) +4+=+4+
and
(1) +5x+-+3y+=+8+
(1) +5%2A%28-2%29+-+3%2A%28-6%29+=+8+
(1) +-10+%2B+18+=+8+
(1) +8+=+8+
OK