Question

$-x + y = 5$
$7x - 6y = -25$
$-x + y = 5$
$7x - 6y = -25$
$overline{square x + square y = square}$

Explanation:

Step1: Add the two equations

$$(-x + y) + (7x - 6y) = 5 + (-25)$$

Step2: Simplify left and right sides

$$(-x+7x)+(y-6y)=5-25$$
$$6x - 5y = -20$$

Answer:

$6x + (-5)y = -20$
(The blanks are filled with 6, -5, -20 respectively)