If you can peel 4 patatoes in 10 minutes how many can you peel in 14
4 potatoes in 10 minutes is 2.5 mins per potato
So, after 12.5 mins, you have peeled 5 potatoes
But, 1.5 mins later (at the 14 mins mark) you are still peeling your 6th potato, but haven't yet finished peeling it, which means that, so far (after 14 mins) you will only have peeled 5 potatoes.
Answer: 5 potatoes