Need help with 19&21

Hello!
To solve questions 19 and 21, firstly, we need to convert the percentages to decimals. There are two ways to convert them.
After finding the converted percentage, you multiply the cost by that decimal. That will be your final answer according to the problem, but that is not true in some cases (like number 19).
19). Sales Tax
We are given a Digital Assistant priced at 399 dollars. We are finding the total price including the sales tax, so we need to add the total price and the sales tax together.
7.75 / 100 = 0.0775
399 × 0.0775 = 30.9225 | This can be rounded to about 30.92 dollars.
399 + 30.92 = 429.92 dollars
The total price including the sales tax is 429.92 dollars.
21). Women in the Navy
Given that there is a 335-person crew, and of which, 13% are female, we need to find how much females are on the navy guided-missile destroyer.
13 / 100 = 0.13
335 × 0.13 = 43.55
Since we are working with humans, we need to round it to a whole number.
Therefore, there are about 44 crew members that are women.
Final answers: