How do you solve the system #2x-3y=21# and #y=3-x# using substitution?

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Answer 1 · 2017-03-03T08:05:00

#x=6# & #y=-3#
Solution : #(6,-3)#

#2x-3y=21# ------------(1)

#y=3-x#-----------------(2)

Substituting eq 2 in eq 1

#2x-3(3-x)=21#

#2x-9+3x=21#

#5x-9=21#

#5x=30#

#x=6#

Put #x=6# in eq 2 we get,

#y=3-6#

#y=-3#

Solution : #(6,-3)#