How do you solve the system of equations #y= 2x + 4# and #- 5x - 5y = - 5#?

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Answer 1 · 2016-12-02T20:40:12

#x = -1# and #y = 2

Because the first equation is already solved for #y# you can substitute #2x + 4# for #y# in the second equation and solve for #x#:

#-5x - 5(2x + 4) = -5#

#-5x - 10x - 20 = -5#

#-15x - 20 = -5#

#-15x - 20 + 20 = -5 + 20#

#-15x = 15#

#(-15x)/-15 = 15/-15#

#x = -1#

Now substitute #-1# for #x# in the first equation and calculate #y#:

#y = (2*-1) + 4#

#y = -2 + 4#

#y = 2