measure angle A is 58 degrees, this means that, the angle bisector divides the angle into two equal angles each of measure 58/2 = 29 degrees
measure angle B is 96 degrees, this means that the angle bisector divides the angle into two equal angles each of measure 96/2 = 48 degrees
In triangle AMB, we know that the sum of all measure of a triangle is 180 degrees and we have measure angle MAB = 29 degrees and measure angle MBA = 48 degrees
Therefore,
measure angle AMB = 180 - (29+48) = 103 degrees