Problem Solving (PS) | Re: Four of the students applying to schools this year are applying only

I originally approached this problem by performing the following calculations: 40-4+6+5+2(5)=20 and got the problem wrong. After reading other poster's answers I see how the answer is 25, however, I'm a little confused as to why we don't multiply the amount of students applying to schools in all three regions by two. Is it because the question prompt already accounts for any overlap? Thank you for your help.

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