Final answer:
Luna's brother's package weighed 5.76 ounces and would weigh 0.576 ounces if it was 1/1000 as much as Luna's.
Step-by-step explanation:
Luna ordered a package from Amazon that weighed 576 ounces. Her brother's package weighed 1/100 as much as Luna's. To find out how many ounces her brother's package weighed, we need to divide Luna's package weight by 100. 576 ounces / 100 = 5.76 ounces. So, her brother's package weighed 5.76 ounces.
If her brother's package was 1/1000 as much as Luna's, we can repeat the same process. 576 ounces / 1000 = 0.576 ounces.
Therefore, her brother's package would weigh 0.576 ounces in this case.