Put the first equation in slope-intercept form, or y = mx + b. Start by subtracting y from both sides.
2x - y = -10, subtract 2x from both sides.
-y = -10 - 2x
Divide both sides by negative one.
y = 10 + 2x
To find the slope when the equations are in slope-intercept form you look at the coefficient of x. The first equation has the slope of 2 (which we just found), and the second equation has the slope of -2.
Parallel lines have the same slope and perpendicular lines have opposite reciprocal slopes. Since 2 and -2 are neither of these, your answer is neither.
