To find the unit rate of push-ups per day, divide the total number of push-ups by the number of days.
Given:
- Total push-ups = 90
- Total days = 3
Now, calculate the unit rate:
\[ \text{Push-ups per day} = \frac{\text{Total push-ups}}{\text{Total days}} = \frac{90}{3} = 30 \]
So, the unit rate is 30 push-ups per day.