Answer:
57
Step-by-step explanation:
Firstly, we will need to calculate what x is.
To calculate this, the important property of the parallelogram to use is that adjacent angles are supplementary.
This means A and B are supplementary while B and C are also supplementary
what we are trying to say is that they add up to be 180
Thus,
5x + 18 + 3x -6 = 180
8x +12 = 180
8x = 180-12
8x = 168
x = 168/8
x = 21
Thus, the measure of angle B is 3x-6 = 3(21) -6 = 63-6 = 57
Now, another important property of parallelograms is that opposite angles are equal. This means that angle B= C = 57
