To find the unit price, you need to divide the total cost by the number of items in the pack.
The 2-pack of erasers costs $1.58, and since there are 2 erasers in the pack, the calculation is:
\[ \text{Unit Price} = \frac{\text{Total Price}}{\text{Number of Items}} = \frac{1.58}{2} = 0.79 \]
So, the unit price of each eraser is $0.79.