The question is asking for the arc of the circle not including the right triangle. So we know one arc is 146 degrees and the right angle is 90 degrees. 146+90=236. The circumference of a circle is 360 degrees so we have to subtract 236 from 360. 360-236=124. 124 degrees is arc BC. So know that we know all angles, we can add up the ones we need. We don’t need the 90 degree angle in the right triangle so we won’t add that. In the end we have 146+124=270. So therefore, the measure (m) of arc ABC is 270 degrees.