How do you solve by substitution #x-3y=-5# and #2x+y=11#?

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Answer 1 · 2015-06-04T21:01:22

First subtract #2x# from both sides of the second equation to get:

#y = 11 - 2x#

Substitute this express for #y# into the first equation to get:

#-5 = x - 3y = x - 3(11-2x) = x-33+6x#

#= 7x - 33#

Add #33# to both ends to get:

#7x=28#

Divide both sides by #7# to get:

#x=4#

Then

#y = 11 - 2x = 11 - (2xx4) = 11 - 8 = 3#