Two angles sit side by side along a straight line and together they fill the whole straight angle. One of them measures 125 degrees. How many degrees does the other one measure?

Explanation

Two angles that complete a straight line must total 180 degrees, so the missing one is 180 minus 125, which leaves 55 degrees. Working from 360 degrees gives 235 degrees instead, and that total belongs to angles that go all the way round a point rather than along a line.