The measure of an angle is 168. What is the measure of its supplementary angle?

12

Step-by-step explanation:

So supplementary angles equal 180:

Lets take the unknown angle as "x"

So 168+x=180

1) subtract 168 from both sides to eliminate it:

X=12

Hope this helps!

Step-by-step explanation:

let x represent the measure of the missing angle

now, since the measures of two supplementary angles add up to 180°

then

168 + x = 180

then

x = 180 - 168

then

x = 12