How many are taking neither subject?

Question

There are 23 students in a classroom. 18 are taking math and 15 are taking science. Six students are taking math but not science.

Answer 1

Please disregard my comment.  The heading states it...  lol

 

If you draw two intersecting circles for a Venn Diagram

 

You have 3 areas...   The intersecting area in the middle is

for students taking both math and science.  The left circle

label math.  The right circle label science.  The middle area

label both.

 

Putting a 6 in the area for math only leaves 12 to put

in the area for taking both.

That means there are 3 taking science only to make the

15 that take science.

So we have:

 

Math only ...    6

Science only... 3

Both ...           12

                    ------

                     21

 

Since we have 23 students, 2 students take neither math nor science.