Supplementary and Complementary Angles

[travis+]

Hello. I managed to get myself stuck on another problem.

I must "Find the measure of an angle if its supplement measures 12° less than three times its complement."

I know that supplementary angles add up to 180 degrees and complementary angles add up to 90 degrees, but I'm not sure how to set up this problem.

My idea was that "s" would be supplementary and "c" would be 1/2 of s, so I tried this:

s = 3 (1/2s) - 12
s = 7/2s - 12
2/2 s = 7/2s - 12
12 = 5/2s
2/5 * 12/1 = 5/2s * 2/5
24/5 = s

And then at this point I'm just like... so confused I'm not even sure what I'm looking for anymore. If the supplementary angle is 24/5, then I guess the angle i'm looking for would be 180 - 24/5, whatever that is... but I don't think that's correct.

Am I going about this the wrong way? Please help!

 

[travis+]

HINT
x = measure of angle
180 - x = 3(90 - x) - 12

Okay, so...

180 - x = 3(90-x) - 12
180 - x = 270 - 3x - 12
2x = 78
x = 39 degrees

Perfect, thank you!

Going through all of these review questions is making me remember what I always hated about Algebra when I was in school. I actually think it is fun, like solving a puzzle, when I know what I'm doing... but the most common struggle for me with Algebra isn't doing the math, but knowing what math to do. Just like here... I wasn't fully understanding what the question was asking and totally set the equation up wrong. I have got to work on that.