How do you solve #3x-7y=28# and #x+4y=3# using substitution?

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Answer 1 · 2018-07-07T08:02:05

#x=7,y=-1#

Adding #-4y# to the second equation

#x=3-4y#

plugging this in the first equation

#3(3-4y)-7y=28#

expanding

#9-12y-7y=28#

adding #-9# to both sides and combining like Terms

#-19y=19#

so
#y=-1# and #x=3+4=7#