To find Albert's unit rate in miles per hour, we need to divide the distance he walks (in miles) by the time it takes him (in hours).
Albert walks \( \frac{4}{5} \) of a mile in \( \frac{5}{12} \) of an hour.
The unit rate can be calculated using the following expression:
\[ \text{Unit Rate} = \frac{\text{Distance}}{\text{Time}} = \frac{\frac{4}{5}}{\frac{5}{12}} \]
So, the expression you can use to calculate his unit rate in miles per hour is:
\[ \frac{\frac{4}{5}}{\frac{5}{12}} \]
Additionally, this can also be simplified as multiplying by the reciprocal:
\[ \frac{4}{5} \times \frac{12}{5} \]
Either expression will lead to the unit rate in miles per hour.