How many students are more in commerce than in law if 1000 students are in
science?

No. of students in Science = 1000

Angle subtended by students in Science = 100°

=> Total no. of students = $$\frac{1000}{100}$$ * 360 = 3600

Angle subtended by students in Commerce = 65°

=> No. of students in Commerce = $$\frac{65}{360}$$ * 3600 = 650

Angle subtended by students in Law = 45°

=> No. of students in Law = $$\frac{45}{360}$$ * 3600 = 450

$$\therefore$$ No. of students more in commerce than in law = 650-450 = 200

(SHORTCUT) :

Since, angle subtended in Science = 100° and no. of students given in Science = 1000

=> 1° = 10 students

Difference in angle between commerce and law = 65-45 = 20°

=> Difference in students = 200 [Since, 1° = 10 students, => 20° = 200 students]