To add these radicals together their radicands must be the same:

7\( \sqrt{28} \) + 7\( \sqrt{7} \)
7\( \sqrt{4 \times 7} \) + 7\( \sqrt{7} \)
7\( \sqrt{2^2 \times 7} \) + 7\( \sqrt{7} \)
(7)(2)\( \sqrt{7} \) + 7\( \sqrt{7} \)
14\( \sqrt{7} \) + 7\( \sqrt{7} \)

Now that the radicands are identical, you can add them together:

To add or subtract terms with exponents, both the base and the exponent must be the same. In this case they are so subtract the coefficients and retain the base and exponent:

-6a² - 7a²
(-6 - 7)a²
-13a²

The area of a circle is given by the formula A = πr² where r is the radius of the circle. The radius of a circle is its diameter divided by two so A = π(\( \frac{d}{2} \))². If the diameter of the logo increases by 60% the radius (and, consequently, the total area) increases by \( \frac{60\text{%}}{2} \) = 30%

The amount of flour you need is (2\(\frac{7}{8}\) - \(\frac{1}{2}\)) cups. Rewrite the quantities so they share a common denominator and subtract:

(\( \frac{23}{8} \) - \( \frac{4}{8} \)) cups
\( \frac{19}{8} \) cups
2\(\frac{3}{8}\) cups

By buying two shirts, Frank will save $38 x \( \frac{20}{100} \) = \( \frac{$38 x 20}{100} \) = \( \frac{$760}{100} \) = $7.60 on the second shirt.

So, his total cost will be
$38.00 + ($38.00 - $7.60)
$38.00 + $30.40
$68.40