If you were to solve the following system by substitution what would be the best variable to solve for and from what equation 2x plus 6y equals 9 3x-12y equals 15?

2x + 6y = 9

3x - 12y = 15

Chose the second equation because you can simplify it.

3x - 12y = 15 divide by 3 to both sides

x - 4y = 5 add 4y to both sides

x = 4y + 5

Replace 4y + 5 for x to the first equation.

2x + 6y = 9

2(4y + 5) + 6y = 9

8y + 10 + 6y = 9

14y = -1

y = -1/14

x = 4y + 5

x = 4(-1/14) + 5

x = -2/7 + 5

x = -2/7 + 35/7

x = 33/7