All three angles in a triangle will always add up to 180°. You know one of them is 49°. To find the angle U, you can see that it falls on a flat line, which is going to equal 180°, so to find that angle you would subtract 109 from 180, giving you 71°. If two of the angles are stated, all you need is to subtract both from 180 to find what your last angle is. So 180°-71°-49° = 60°
#4 I think is 75, but I don't feel like explaining it.
