Question

how to do complementary and supplementary angles

Answer 1

complementary angles add up to 90 and supplementary angles add up to 180.

For example, if you had two angles that together add up to 90(you can tell by seeing that they form a right angle) and you only know one angle measure, and say its 50, you would do 50+x=90. Isolate x and you get that the angle would be 40. You do the same for supplementay angle except the angles would form a line so the equation would read 50+x=180.