3x - 4y = 12

2x + 6y = 18

Choose all of the equations that could be used when solving this system by substitution.

x = 9 - 3y

y = 18 - 3x

y = 3x + 3

x = 4

3

y + 4

Answer: x = 9 - 3y

Step-by-step explanation:

Hi, to answer this question we have to solve the system by substitution:

a) 3x - 4y = 12

b) 2x + 6y = 18

If we isolate "y" on b)

2x + 6y = 18

2x = 18 - 6y

x = 18/2 - 6/2y

x = 9 - 3y is a possible equation

Doing the same thing with the other equation a), and isolating "y" in both expressions, the only possible equation is the one founded above.