Question 1142803
<br>
18 studying Korean and 10 studying both Japanese and Korean  -->  8 studying Korean only.<br>
23 studying Japanese and 10 studying both Japanese and Korean  -->  13 studying Japanese only.<br>
So....<br>
Japanese only: 13
Korean only: 8
both: 10
neither: 40 - (13+8+10) = 40-31 = 9