Answer: m<C = 45, m<M = 50, m< B = 85.
Explanation:
Adjacent angles on a line sum to 180 degrees.
m<C + m<M + m<B = 180. 45 + (8x+10) + (12x+25) = 180. Combine like terms. 80+ 20x =180. Subtract 89 from both sides. 20x = 100. Divide both sides by 20. X = 5. Substitute x back into the angle measures. m<C = 45, m<M = 50, m< B = 85.