A Mathematics competition consists of 30 multiple-choice questions. A
1 answer:
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Answer:
1 student
Step-by-step explanation:
From the Vann diagram attached below,
Let x represent the number of students who took 3 subjects.
Therefore,
100 = (42-9-11-x)+11+x+9+10+(35-10-11-x)+(30-9-10-x)+20
100 = 22-x+11+x+9+10+14-x+11-x+20
100 = 97-2x
2x = 100-97
2x = 3
x = 3/2.
x = 1.5
x = 1 student
