Set theory, logic problem. pls. help?

N

naturalnumber

New member
in a certain experiment in chemistry, the following number of students used the reagents A, B, and C.
18 students used all the reagents A, B, and C
23 students used reagent A and B
25 students used reagent A and C
20 students used reagent B and C
4 students used reagent A only
9 students used reagent B only
10 students used reagent C only.

1. how many students were there in the class?
2. How many students used reagent A and B only?
3. how many students used reagent C?

my answers are
1. 105 students in the class
2. 5 students used reagent a and b only
3. 37 students used reagent C

pls. provide explanation if you think my answers were wrong

thanks
 
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