√1÷ײ × √ײ÷81 is equivalent to which of the following products ×÷9 , 1÷9, 1 ÷81, ×÷81

Three times the sum of a number and seven is negative thirty-six. what is the number?

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

Which of the following vectors are orthogonal to (2,1)? check all that apply