Answer:
8 lb box
Step-by-step explanation:
Find which laundry detergent has a lower unit price
The unit price is how much something costs for a single unit
In this case, it is how much the detergent costs for 1 pound
7.4/8 lbs = 0.925 dollars per lb
5.38/4 lbs = 1.345 dollars per lb
Since 1.345 > 0.925, the 8 lb box is a better buy