Two angles are supplementary. They have measures of (7x+2) degrees and (3x-2) degrees. What is the value of x?

Question

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Answer 1

Hi Bob.

When two angles are supplementary, it means they add up to 180 degrees. So you have an angle of (7x+2) degrees and another of (3x-2) degrees that add up to 180 degrees.  In math, this looks like:

7x+2+3x-2=180.

From here, it's all algebra.  The +2 and -2 cancel.

7x+3x=180. The 7x and 3x add to 10x.

10x=180.  Now we divide both sides by 10.

x=18.

Check:

Let's plug this back in and check that the angles do actually add to 180 degrees.

7(18)+2+3(18)-2=126+2+54-2=128+52=130+50=180.

Correct.

 

Answer 2

Hi Bob,

 

Supplementary angles add up to 180 degrees. Therefore,

(7x+2) + (3x-2) = 180

10x = 180

x = 18 degrees