By buying two shirts, Charlie will save $10 x \( \frac{15}{100} \) = \( \frac{$10 x 15}{100} \) = \( \frac{$150}{100} \) = $1.50 on the second shirt.

So, his total cost will be
$10.00 + ($10.00 - $1.50)
$10.00 + $8.50
$18.50

Use PEMDAS (Parentheses, Exponents, Multipy/Divide, Add/Subtract):

3 + (3 + 5) ÷ 3 x 2 - 4²
P: 3 + (8) ÷ 3 x 2 - 4²
E: 3 + 8 ÷ 3 x 2 - 16
MD: 3 + \( \frac{8}{3} \) x 2 - 16
MD: 3 + \( \frac{16}{3} \) - 16
AS: \( \frac{9}{3} \) + \( \frac{16}{3} \) - 16
AS: \( \frac{25}{3} \) - 16
AS: \( \frac{25 - 48}{3} \)
\( \frac{-23}{3} \)
-7\(\frac{2}{3}\)

To multiply terms with radicals, multiply the coefficients and radicands separately:

7\( \sqrt{2} \) x 9\( \sqrt{4} \)
(7 x 9)\( \sqrt{2 \times 4} \)
63\( \sqrt{8} \)

Now we need to simplify the radical:

63\( \sqrt{8} \)
63\( \sqrt{2 \times 4} \)
63\( \sqrt{2 \times 2^2} \)
(63)(2)\( \sqrt{2} \)
126\( \sqrt{2} \)

A number in scientific notation has the format 0.000 x 10^exponent. To convert to scientific notation, move the decimal point to the right or the left until the number is a decimal between 1 and 10. The exponent of the 10 is the number of places you moved the decimal point and is positive if you moved the decimal point to the left and negative if you moved it to the right:

0.0008325 in scientific notation is 8.325 x 10^-4

To find the average of these 4 numbers add them together then divide by 4:

\( \frac{8 + 6 + 9 + 5}{4} \) = \( \frac{28}{4} \) = 7