Final answer:
To find the measure of angle B in the given problem, we substitute the given expression for B into the equation for supplementary angles and solve for x. The value of x is 50 degrees, so the measure of angle B is 50 degrees.
Step-by-step explanation:
The given problem states that A and B are a pair of supplementary angles, where A = 30 + 2x and B = x. To find the measure of angle B, we substitute the given expression for B into the equation for supplementary angles. We have:
30 + 2x + x = 180
Combining like terms, we get 3x + 30 = 180. Subtracting 30 from both sides gives us 3x = 150. Dividing both sides by 3, we find x = 50.
Therefore, the measure of angle B is x, which is 50 degrees.