教授, 請幫我看看這道題吧, 是不是題有問題呀? 謝謝先 :)

 Problem of the Week

In grade 11, science students can select a course in Physics, Biology or Chemistry. 18 selected Physics, 32 selected Biology, and 25 selected chemistry. Of these, 16 chose both Biology and Chemistry, but only 7 chose both Physics and Chemistry and only 8 selected both Physics and Biology. Just 3 selected to take all three courses. How many science students are there all together?

請您看看答案是  38, 還是 41