How do you solve the system of equations #-x + 2y = 21# and #5x + 6y = 23#?

1 Answer
Lucy
May 12, 2018

#x=-5#
#y=8#

Explanation:

#-x+2y=21# --- (1)
#5x+6y=23# --- (2)

From (1),
#-x+2y=21#
#x=2y-21# --- (3)

Sub (3) into (2)

#5(2y-21)+6y=23#
#10y-105+6y=23#
#16y=23+105#
#16y=128#
#y=8# --- (4)

Sub (4) into (3)
#x=2y-21#
#x=2(8)-21#
#x=-5#

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