Since you want to cancel x-terms, you're only concerned with the x-term coefficients, 5 and 4. You will want to use the opposite of one of these. It usually works well to multiply the equation with the least y-coefficient by the negative multiplier. That is ...
Vertical angles are always congruent, which means that they are equal. Adjacent angles are angles that come out of the same vertex. Adjacent angles share a common ray and do not overlap. The size of the angle xzy in the picture above is the sum of the angles A and B.