To find the unit rate of minutes Bella spent in yoga class each day, you can divide the total number of minutes by the number of days.
Total minutes spent = 128 minutes
Number of days = 4 days
Now, calculate the unit rate:
\[ \text{Unit rate} = \frac{\text{Total minutes}}{\text{Number of days}} = \frac{128 \text{ minutes}}{4 \text{ days}} = 32 \text{ minutes per day} \]
So, Bella spent 32 minutes in yoga class each day.