To find the unit cost per shirt, you need to divide the total cost by the number of shirts.
Given that the total cost for 3 shirts is $24.60, you can calculate the cost per shirt as follows:
\[ \text{Unit cost per shirt} = \frac{\text{Total cost}}{\text{Number of shirts}} = \frac{24.60}{3} \]
Calculating that:
\[ \text{Unit cost per shirt} = 8.20 \]
Therefore, the unit cost per shirt is $8.20.