Answer:
60
Explanation:
All triangles have a total measurement of 180 degrees. So to find the last angle measure subtract 90 and 30 from 180, 180-(90+30). This equals 60 degrees. Additionally, a triangle with a 90 and 30 degree angle is known as a 30-60-90 special right triangle. All of these triangles will have 60 as their third measurement.