The best answer would be C
Answer:
<h2>
<em>7</em><em>2</em><em>.</em><em>9</em><em>°</em></h2>
<em>sol</em><em>ution</em><em>,</em>
<em>
</em>
<em>hope</em><em> </em><em>this</em><em> </em><em>helps</em><em> </em><em>.</em><em>.</em><em>.</em><em>.</em>
<em>Good</em><em> </em><em>luck</em><em> on</em><em> your</em><em> assignment</em><em>.</em><em>.</em><em>.</em>
Given problem;
A = 4 π R²
To solve for R, we have to make it the subject of the expression.
Since
A = 4 π R² , follow these steps to find R;
Multiply both sides by
A x
=
x 4 π R²
= R²
Then find the square root of both sides
√R² =
R = 
The solution is 
(1 + x) (13) = 13+6.5
13x + 13 = 19.5
13x = 6.5
x = 0.5
The item was marked up by 50%
Divide the total amount of money Janice has by the cost of the stamps.
$7.20 / $0.30 = 24
Janice can buy 24 stamps.