the sum of three angles of a triangle adds up to 180 degrees. In this problem, you are given two angles.
x+(2x+15)+the measure of angle Q should equal 180.
Since everything is addition, the parenthesis can be removed.
x+2x+15+Q=180. This can then be simplified to 2x+15+Q=180. Subtract 15 from both sides to get 2x+Q=165. Divide both sides by two to get the x by itself. x+Q=82.5.
Unfortunately I don't really know what to do from here, but I hope it helped at least a little.