For 17, 14x-25=129, add 25 to 129 to get 154, then divide 154 by 14x to get x=11. The conditional for 17. would be "If J║K then alternate interior angles are congruent.
For 18. 2x-8+9x-10=180, combine like terms to get 11x - 18 =180, add 18 to 180 to get 198 than divide 198 by 11x and get x = 18. Converse statement would be, "If J║K then consecutive interior angles are supplementary.
