Determine each of the following percents without using a calculator. Show your work or explain your thinking for each problem.

1. $20\%$ of $$24$

   Hint (a):

   $10\% \text{ of } $24 \text{ is } $2.40$
   $20\% \text{ is } 2\left(10\%\right)$

   Answer (a):

   $$4.80$

2. $30\%$ of $$24$

   Hint (b):

   This problem is very similar to part (a).

3. $5\%$ of $$24$

   Hint (c):

   $5\%$ is one half of $10\%$

4. $15\%$ of $$24$

   Hint (d):

   $15\% \text{ is } 10\% + 5\%$

   Answer (d):

   $$3.60$