Help please ASAP thank you

What is the missing reason in step 5? linear pair postulategivendefinition of complementary anglescongruent complements theorem

Which shows the correct solution of the equation 1/2a+2/3b=50, when b=30?

Select 2 statements that are true about the equation y+6=-10(x-3).1) the slope of the line is -102) the slope of the line is 33) one point on the line is (3,6)4) one point on the line is (3,-6)