For #3 these angles are alternate exterior angles. (Opposite sides of the transversal and outside of the parallel lines) Alternate exterior angles are equal, so set these two equal to each other to solve for x. 27x-1 = 80 Add 1 to both sides. 27x = 81. Divide both sides by 27. X = 3. For #4, these angles are same side interior angles. (Same side of the transversal and inside the parallel lines) Same side interior angles sum to 180 degrees. (5x+5) + (9x+21) = 180. Combine like terms. 14x + 26= 180. Subtract 26 from both sides. 14x = 154. Divide both sides by 14. X = 11
