∠A and \angle B∠B are complementary angles. If m\angle A=(x+9)^{\circ}∠A=(x+9)
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and m\angle B=(7x-15)^{\circ}∠B=(7x−15)
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, then find the measure of \angle B∠B.

To find the complement of an angle x, subtract x's measurement from 90 degrees: 90 degrees - x degrees = the measure of x's complementary angle. To find the supplement of an angle y, subtract y's measurement from 180 degrees: 180 degrees - y degrees = the measure of y's supplementary angle.

Step-by-step explanation: