If a pair of vertical angles measure 5x-51 and 3x-21, find the measure of the angles

Vertical angles are always equal so:

5x-51=3x-21

Subtract 3x on both sides

2x-51=-21

Add 51 on both sides

2x=30

Divide by 2 on both sides

x=15 so the measures are 15 (insert whatever unit of measurement)