How do you find the value of y that makes (3,y) a solution to the equation #3x-y=4#?

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Answer 1 · 2015-04-09T13:40:51

If (3,y) is a solution to #3x-y=4#, we can substitute #x=3# in the equation.

We get

#(3*3) - y = 4#

# 9 - y = 4#

Transposing 9 to the right hand side, we get

# - y = 4 - 9 #

# - y = -5#

Multiplying both sides with #-1#, we get

#color(green)( y = 5#