In △ABC, if the ratio of angles is in the proportion 3 : 5 : 4, then the difference between the biggest and the smallest angles (in degrees) is:

20° 25° 30° 35°

35°

Total sum of angles in a triangle = 180° Here, the proportion of angles = 3 : 5 : 4 Thus, 12r = 180°             r = 15 Biggest angle = 5r = 5 x 15 = 75° Smallest angle = 3r = 3 x 15 = 45° Difference between them = 75 - 45 = 30°