Question

If two angles are supplementary, they must __________.

add up to
add up to
be adjacent
be congruent

Answer 1

If two angles are supplementary, their sum is 180º and they can be expressed as x and 180-x. If they are congruent ,then the two angles are equal:
x=180-x
2x=180
x=90º and 180-x=90º
The 2 angles have to add to 180 degrees

Answer 2

supplementary angles add up to 180