6) corresponding angles are equal. 45x=46x-2. -x=-2. x=2. 7) same side interior angles. add up to 180. x+140+x+60=180. 2x=-20. x=-10. 8) alternate exterior angles are equal. 16x+9=4+17x. -x=-5. x=5. 9) same side interior angles. add up to 180. 19x+1+9x+11=180. 28x=168. x=6.