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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?
Wiki User
∙ 13y ago
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
Wiki User
∙ 13y ago
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