To determine how much more weight the trolley can hold, we first need to convert everything into the same unit. The trolley can hold a total of 20 lbs.
Starr put on 12 lbs 8 oz of groceries. Since there are 16 ounces in a pound, we need to convert the ounces to pounds:
8 oz รท 16 oz/lb = 0.5 lbs
Now we can add that to the weight Starr put on the trolley:
12 lbs + 0.5 lbs = 12.5 lbs
Now, we subtract the weight of the groceries from the total capacity of the trolley:
20 lbs - 12.5 lbs = 7.5 lbs
Thus, the trolley can hold an additional 7.5 lbs of groceries.