Answer:
6.7 minutes
Explanation:
From what we know, we will have to divide. The things we are dividing are the 30 minutes it took to make the 40 plastic harmonicas and the total we need of harmonicas, which is 200. By dividing 200 by 30, we get 6.666666666666667. But, we can't have that long answer, so we need to round up. Which is when we get our quotient of 6.7 minutes. If I'm wrong, please, don't be afraid to correct me. And have a good day stranger!
Edit: This answer is wrong. I was corrected and now I know what the answer is. Please do avoid this answer. But have a good day to anyone sees this!