How do you find the measures of the angles of a triangle if the measure of one angle is twice the measure of a second angle and the third angle measures 3 times the second angle decreased by 12?
To be certain I understand your question correctly, you have a triangle, where you with "measures" mean number of degrees each angle is.
I.e. let the triangle look something like this:
If my understanding of your question is correct, we have
The angles in the triangle, therefore, are
This gives the following triangle: