all 3 angles need to equal 180 degrees
the right angle = 90 degrees
so the other 2 angles need to equal 180 - 90 = 90 degrees
so now you have x +15 + 2x =90
combine like terms 3x +15 = 90
subtract 15 from each side: 3x = 75
divide each side by 3: x = 75/3 = 25
x = 25
x+15 = 25+15 = 40
2x = 2*25 = 50
the larger angle is 50 degrees