Answer:
divide the cost by the number of pounds she bought to obtain the cost of one pound
11 divided by 2 3/4
since 2 3/4 = 11/4 and 4/11 is the reciprocal of 11/4
11 divided by 2 3/4 = 11 divided by 11/4 = 11 times 4/11 = 4
meaning she bought it at a price of 4$ per pound
then you find the difference between the price she paid from the price they are on sale
4 - 2 = 2