1.-First, notice that angle WOV and angle WOX are complementary, this means that we have the following equation:

since the measure of angle WOX is 30 degrees, we have the following:

2.- To find the measure of angle YOZ, we can see that it is vertical with angle WOV, thus, we have:

therefore, the measure of angle YOZ is 60 degrees since it is vertical with angle WOV