Answer:m∠B = 132°
Step-by-step explanation:
In a quadrilateral inscribed in a circle, opposite angles are supplementary. So, angle B + angle D = 180 degrees2Given angle B = 3x - 12 and angle D = x, substitute these into the equation33x - 12 + x = 1804Combine like terms: 4x - 12 = 1805Solve for x: 4x = 192, x = 486Substitute x back to find angle B: 3(48) - 12 = 132 degrees