How do you solve #x+y=7# and #2x+3y=20#?

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Answer 1 · 2015-05-18T00:13:26

We can isolate one variable in one equation and substitute it in the other one.

Let's isolate #x# in the first equation and then substitute it in the second one:

#x=7-y#

Then

#2(7-y)+3y=20#
#14-2y+3y=20#
#y=6#

If #y=6# and #x=7-y#, then #x=7-6#, #x=1#!

There you have: #x=1# and #y=6#!