Question

1a. which variable is eliminated (canceled out) when the two equations are combined (added together)?
\

$$\begin{cases}10x + 2y = -26\\\\-7x - 2y = 20\\end{cases}$$

\bigcirc x
\bigcirc y

Explanation:

Step1: Add the two equations

$$(10x + 2y) + (-7x - 2y) = -26 + 20$$

Step2: Simplify the left side

$$10x - 7x + 2y - 2y = 3x + 0y$$

Step3: Identify canceled variable

The $y$-terms sum to 0.

Answer:

y