How do you solve x-y=0 and 12x-5y=-21?

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Answer 1 · 2015-10-14T06:33:16

The solution is
#color(blue)(x=-3,y=-3#

#x-y=0#
#x=color(blue)(y#......equation #1#

#12x-5y=-21#....equation #2#

Substituting #1# in #2#

#12x-5y=-21#

#12* (color(blue)(y))-5y=-21#

#12y-5y=-21#

#7y=-21#

#y=-21/7#

#color(blue)(y=-3#

And since #x=y#
#color(blue)(x=-3#