Step 1: Calculate the time to eat one whole pizza
Donna eats 1/4 of a pizza in 1 minute. Therefore, the time it takes for her to eat one whole pizza is:

Time for one pizza=4×1 minute=4 minutes\text{Time for one pizza} = 4 \times 1 \text{ minute} = 4 \text{ minutes}Time for one pizza=4×1 minute=4 minutes

Step 2: Calculate the time to eat 2.5 pizzas
Now that we know it takes Donna 4 minutes to eat one pizza, we can find the total time for 2.5 pizzas by multiplying the time for one pizza by 2.5:

Total time=2.5×4 minutes=10 minutes\text{Total time} = 2.5 \times 4 \text{ minutes} = 10 \text{ minutes}Total time=2.5×4 minutes=10 minutes

Conclusion
Thus, it will take Donna 10 minutes to eat 2.5 pizzas.