The problem you're working on asks to calculate the unit rate of Chen's biking speed, given that Chen bikes $2 \frac{1}{2}$ miles in $\frac{5}{12}$ of an hour.

To calculate the unit rate (miles per hour), follow these steps:

1. Convert mixed fraction to improper fraction:
   $2 \frac{1}{2} = \frac{5}{2} \text{ miles}$

2. Set up the unit rate calculation:
   The unit rate is the distance divided by the time: $\text{Unit rate} = \frac{\frac{5}{2} \text{ miles}}{\frac{5}{12} \text{ hours}}$

3. Divide the fractions:
   Dividing by a fraction is the same as multiplying by its reciprocal: $\frac{5}{2} \div \frac{5}{12} = \frac{5}{2} \times \frac{12}{5}$

4. Simplify the expression:
   The $5$'s cancel out, leaving: $\frac{12}{2} = 6$

So, Chen's unit rate is 6 miles per hour.

The answer you entered (1.04 miles per hour) is incorrect. The correct answer is 6 miles per hour.

Do you need further details or clarifications? Here are 5 related questions to practice:

1. How do you convert a mixed fraction into an improper fraction?
2. How do you divide fractions in general?
3. If Chen biked 3 miles in $\frac{3}{4}$ of an hour, what would his speed be?
4. What is the significance of unit rate in real-world problems?
5. How can simplifying fractions help in solving rates and ratios?

Tip: When dividing by a fraction, remember to multiply by its reciprocal!