To take the square root of a fraction, break the fraction into two separate roots then calculate the square root of the numerator and denominator separately:

\( \sqrt{\frac{36}{81}} \)
\( \frac{\sqrt{36}}{\sqrt{81}} \)
\( \frac{\sqrt{6^2}}{\sqrt{9^2}} \)
\(\frac{2}{3}\)

The distributive property for multiplication helps in solving expressions like a(b + c). It specifies that the result of multiplying one number by the sum or difference of two numbers can be obtained by multiplying each number individually and then totaling the results: a(b + c) = ab + ac. For example, 4(10-5) = (4 x 10) - (4 x 5) = 40 - 20 = 20.

By buying two shirts, Charlie will save $18 x \( \frac{20}{100} \) = \( \frac{$18 x 20}{100} \) = \( \frac{$360}{100} \) = $3.60 on the second shirt.

By buying two shirts, Damon will save $11 x \( \frac{15}{100} \) = \( \frac{$11 x 15}{100} \) = \( \frac{$165}{100} \) = $1.65 on the second shirt.

So, his total cost will be
$11.00 + ($11.00 - $1.65)
$11.00 + $9.35
$20.35

The factors of a number are all positive integers that divide evenly into the number. The factors of 20 are 1, 2, 4, 5, 10, 20.