To determine how many pages Henry reads per minute, we calculate as follows:

Henry reads 90 pages in 30 minutes. To find pages per minute:

$\text{Pages per minute} = \frac{\text{Total pages}}{\text{Total minutes}} = \frac{90}{30} = 3$

Answer: Henry reads 3 pages per minute.

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Do you want additional details or have further questions?

Here are five related questions to explore:

1. How many pages does Henry read in an hour at this rate?
2. If Henry increases his reading speed by 20%, how many pages would he read per minute?
3. How long would it take Henry to read a 300-page book?
4. If Henry reads for 15 minutes, how many pages does he finish?
5. How many pages would Henry read in 45 minutes at the same speed?

Tip: To calculate rates like this in real life, divide the total by the time or quantity to find the per-unit value!