When finding the common denominator between fractions, which value can be helpful, GCF, or LCM? How?

The answer would be GCF because when you finding the common denominator GCF is how you do it. at least thats what I do and I got it right! :p

hope this helps! :) I don't really know how to explain lol

do you mean add both of the equations together

because if you do the answer is 10x-5

step-by-step explanation:

x = -3

y = -18

step-by-step explanation:

to solve by substitution, substitute one variable and solve for the other. then substitute again to find the remaining variable.

x-1/3(3x-9) = -3 since y=3x-9 substittute y.

x-1/3(3x-9)=-3

x + x +3 = -3

2x+3=-3

2x+3-3= -3-3

2x=-6

x=-3

substitute again into y=3x-9

y=3(-3)-9

y=-9-9

y=-18