The single-variable equation she solves after substituting is 3x−(−4x+2)=9
They are expressions separated by an equal sign.
Given the system of equations:
To get the required single-variable equation, we will substitute equation 1 into 2 to have:
3x - y = 9
3x - (-4x + 2) = 9
Expand
3x + 4x - 2 = 9
7x = 9 + 2
7x - 11 = 0
Hence the single-variable equation she solves after substituting is 3x−(−4x+2)=9
Learn more on single-variable equation here: https://brainly.com/question/10839449