How do you solve #y=2x+9# and #y=9x +10# using substitution?

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Answer 1 · 2018-04-26T22:49:44

#x = -1/7# and #y = 8 5/7#

Take one y value and substitute it as the y value in the other equation.

Let's use #y = 2x + 9# to substitute in the other equation

#2x + 9 = 9x + 10#

Subtract 2x from both sides, then subtract 10 from both sides.

#9 = 7x + 10#
#-1 = 7x#

Divide both sides by 7

#-1/7 = x#

Now apply your new x value to the first equation, #y = 2x + 9#

#y = (2*-1/7) + 9#
#y = -2/7 + 9#
#y = 8 5/7#