Question

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

Answer 1

2x + 6y = 9 , 3x -12y = 15

3x - 12y = 15 3x = 12y + 15 x = 4y + 5

+12y +12y /3 /3

2x + 6y = 9 , x = 4y + 5

2(4y + 5) + 6y = 9 2x + 6(-1 / 14) = 9

8y + 10 + 6y = 9 2x - (3/7) = 9

14y + 10 = 9 2x = 66 / 7

14y = -1 x = 33 / 7

/14 /14

y = -1 / 14