Answer:
The unit price is $1.19. Her error was that instead of dividing by 4 dozen (48) she just divided by 4.
Explanation:
First to calculate the unit price you must divide the total price (57.12) by the amount of pairs they received (4*12= 48). 4 dozen is 48 since there is 12 in a dozen.
57.12/48= 1.19
Thus 1.19 is the unit price.