Well from what we know about triangle is that they all add up to 180 degrees!
A right triangle would have a 90 degree angle and from the given measurements we know that the other on is 24 degrees.
So we simply subtract!!
180 - 90 = 90 degrees
90 - 24 = 66 degrees
So the measure of the third angle is 66 degrees. :)
Hope this helps. c:
