On #9, you subtract 158 from 180 because its a 180degree angle. so once you solve 180-158 which is 22. you then add 22 to 58 and then subtract your answer from 180 because all of the angles of a triangle should add up to 180. The answer to #9 is 100
The exterior angle is equal to the 2 remote interior angles. For example, #7 is 80 degrees because the two remote angles(54 and 26) added together equal 80 degrees. Also, #9 would be 100 because the exterior angle is given to you. Since the 2 remote angles equal the exterior, all you do is 158+58=100
