Step by step
The question
Question: 60 students were asked.
35 read comics, 25 read novels, and 12 read both.
One is picked at random.
What is the probability they do not read novels?
1 Start in the middle
12 read both.
They go in the middle, where the circles overlap.
2 Fill the rest
35 read comics, but 12 of them are already in the middle.
35 minus 12 is 23.
Novels only: 25 minus 12 is 13.
Neither: everyone else.
60 minus 23, 12 and 13 is 12.
3 Find the part we want
Not novels: everything outside that circle.
23 and 12.
23 plus 12 is 35.
4 Write the fraction
So the probability is 35/60.
Both 35 and 60 can be divided by 5.
That makes it simpler.
So it is 7/12.
5 Check
Let's check: the four parts add up to 23 plus 12 plus 13 plus 12.
That is 60, everyone.
So the answer is right!
Let's look back.
First: start in the middle.
Then: fill the rest.
Then: find the part we want.
Then: write the fraction.
Last: check.