How would this be solved???

Write numerical coefficient of y² in the expression 2x² - 15xy – 7y²

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

Simplify 1/3 12x - 6 a. -2x-1 b.-2x-8 c.-x+4 d.3x+10 e. 4x-2