How do you solve #4x+5y=12# and #-9+y=71# using substitution?

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Answer 1 · 2018-05-13T17:52:43

#x = -97 and y=80#

Substitution will be a good method in this case because there is a single #y# in the second equation.

#y = 71+9=80#

#4x +5y = 12#

#4x +5(80) = 12#

#4x = 12-400#

#4x = -388#

#x =-97#

Check for #x=-97 and y=80#

#4(-97) +5(80)=12#