# Substitution method to solve system of equations

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y - 2x = -5
3y - x = 5

• Substitution method to solve system of equations -

change to first equation to
y = 2x - 5

now sub that into the second one

3y - x = 5
3(2x-5) - x = 5
6x - 15 - x = 5
5x = 20
x = 4

now put that value of x into y = 2x - 5
y = 2(4) - 5
= 8-5
= 3

check in
#1 : 3 - 8 = -5 checks!
#2 : 9 - 4 = 5 checks!

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