To calculate the percentage increase in prices from 2017 to 2018, you'll typically need specific data about the price levels or consumer price index (CPI) for those years, as well as the quantities and prices of the goods involved.
However, since you didn't provide the specific values needed to perform the calculations, I can't calculate the exact percentage increase in prices for you.
If you provide the relevant information (like the prices of pens and books in both years, or the overall price index), I can help you determine the percentage increase in prices.