How to find if an equation is parallel perpendicular or neither?

Look at the gradient of both the equations (the x multiplier, usually known as m), and there are a couple of rules:

Parallel: The gradients are identical
Perpendicular: Look at the gradients as fractions. To get the perpendicular to a gradient you flip the fraction and change the sign. If this is the case for the two gradients, then they are perpendicular.