Subject: mathqa
Question: there are 1000 students in a school and among them 30 % of them attends chess class . 10 % of the students who are in the chess class are also enrolled for swimming . no other students are interested in swimming so how many will attend the swimming class if all enrolled attends ?
Option: 
A: 100
B: 20
C: 30
D: 10
Answer: C