<p>You are given a <strong>0-indexed</strong> 2D integer array <code>brackets</code> where <code>brackets[i] = [upper<sub>i</sub>, percent<sub>i</sub>]</code> means that the <code>i<sup>th</sup></code> tax bracket has an upper bound of <code>upper<sub>i</sub></code> and is taxed at a rate of <code>percent<sub>i</sub></code>. The brackets are <strong>sorted</strong> by upper bound (i.e. <code>upper<sub>i-1</sub>< upper<sub>i</sub></code> for <code>0 < i < brackets.length</code>).</p>
<p>Tax is calculated as follows:</p>
<ul>
<li>The first <code>upper<sub>0</sub></code> dollars earned are taxed at a rate of <code>percent<sub>0</sub></code>.</li>
<li>The next <code>upper<sub>1</sub> - upper<sub>0</sub></code> dollars earned are taxed at a rate of <code>percent<sub>1</sub></code>.</li>
<li>The next <code>upper<sub>2</sub> - upper<sub>1</sub></code> dollars earned are taxed at a rate of <code>percent<sub>2</sub></code>.</li>
<li>And so on.</li>
</ul>
<p>You are given an integer <code>income</code> representing the amount of money you earned. Return <em>the amount of money that you have to pay in taxes.</em> Answers within <code>10<sup>-5</sup></code> of the actual answer will be accepted.</p>
<strong>Input:</strong> brackets = [[3,50],[7,10],[12,25]], income = 10
<strong>Output:</strong> 2.65000
<strong>Explanation:</strong>
Based on your income, you have 3 dollars in the 1<sup>st</sup> tax bracket, 4 dollars in the 2<sup>nd</sup> tax bracket, and 3 dollars in the 3<sup>rd</sup> tax bracket.
The tax rate for the three tax brackets is 50%, 10%, and 25%, respectively.
In total, you pay $3 * 50% + $4 * 10% + $3 * 25% = $2.65 in taxes.
