degree measure of an angle is 40° less than 3 times the degree measure of its supplementary angle, what is the degree measure of the angle?
A.
50°
B.
55°
C.
125°
D.
130°

Question

degree measure of an angle is 40° less than 3 times the degree measure of its supplementary angle, what is the degree measure of the angle?
A.
50°
B.
55°
C.
125°
D.
130°

mathstudent55 · Answer

Do you know what supplementary angles are?

anonymous · Answer

180 degrees

kash_thesmartguy · Answer

Angles which have a sum of 180degrees!

mathstudent55 · Answer

Correct.
Two angles whose measures add up to 180 degrees.

mathstudent55 · Answer

Let's call for now the angles x and y.
From the fact they are supplementary, we know:
x + y = 180

anonymous · Answer

yes

anonymous · Answer

90 plus 90

anonymous · Answer

are u there

mathstudent55 · Answer

90 plus 90 is an example of two supplementary angles
Now let's see what our supplementary angles measure.

anonymous · Answer

so the answer would be c then

mathstudent55 · Answer

Once again, the angles measure x and y.
x + y = 180
Let's solve this equation for y:
y = 180 -x

That means the two angles measure x and 180 - x

mathstudent55 · Answer

Now we use the given info.
"an angle is 40° less than 3 times the degree measure of its supplementary angle"

x = 3(180 - x) - 40

3(180 - x) - 40 + 180 - x = 180

540 - 3x - 40 - x = 0

-4x + 500 = 0

-4x = -500

x = 125

mathstudent55 · Answer

Correct. The answer is C. 125 deg.