Given that the two angles form a linear pair, let second angle be x, the first angle will be 3x because it is 3 times the second angle. But linear angles add up to 180, thus
x+3x=180
4x=180
hence
x=180/4
x=45°
thus the measure of the first angle will be :
3x=3*45=135°
the second angle is 45°