By setting up an equation based on the fact that opposite angles in a parallelogram are equal, solving for x, and then using the measure of angle A to find angle B, we determine that the measure of angle B is 154 degrees.
In a parallelogram, opposite angles are equal. Therefore, we can set up an equation based on the given information about angles A and C:
Angle A = Angle C
6x + 8 = 13x - 13
Now, solve for x:
7x = 21
x = 3
Now that we know the value of x, we can find the measure of angle B. Angle B is adjacent to angle A, so we can use the measure of angle A to find angle B:
Angle B = 180 degrees - Angle A
Angle B = 180 degrees - (6(3) + 8)
Angle B = 180 degrees - 26
Angle B = 154 degrees
So, the measure of angle B in parallelogram ABCD is 154 degrees.