How do you solve this system of equations #3x + y = - 3; y = x + 5#?

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Answer 1 · 2016-12-15T18:36:50

#x = -2# and #y = 3#

Because the second equation is already solved for #y# we can substitute #x + 5# for #y# in the first equation and solve for #x#:

#3x + (x + 5) = -3#

#3x + x + 5 = -3#

#4x + 5 - 5 = -3 - 5#

#4x + 0 = -8#

#4x = -8#

#(4x)/4 = -8/4#

#(cancel(4)x)/cancel(4) = -2#

#x = -2#

Now we can substitute #-2# for #x# in the second equation and calculate #y#:

#y = -2 + 5#

#y = 3#