If a line segment has endpoints a(3x + 5, 3y) and b(x − 1, −y), what are the coordinates of the midpoint of ab ?
(x + 3, 2y)
(2x + 3, y)
(2x + 2, y)
(4x + 4, 2y)

Given: lines a and b are parallel and line c is a transversal. prove: 2 is supplementary to 8 what is the missing reason in the proof? statement reason 1. a || b, is a transv 1. given 2. ∠6 ≅ ∠2 2. ? 3. m∠6 = m∠2 3. def. of congruent 4. ∠6 is supp. to ∠8 4. def. of linear pair 5. ∠2 is supp. to ∠8 5. congruent supplements theorem corresponding angles theorem alternate interior angles theorem vertical angles theorem alternate exterior angles theorem