He should buy 32 feet of fencing. I got 32 by just finding the perimeter or in other words adding 10+10+6+6 which equal 32. You would NOT do area or 10×6 because that would include that land within the fenced area and who wants 60 feet of fencing that you can't put anything in?
Good luck, hope that helped.
We have the following function:

So if we graph this function we will get the Figure below. Thus, let's study both the equation and the graph to get some conclusions. Therefore, we can assure these statements:
First. The function is defined only for

as shown in the Figure. This is also true because of

where

must be greater (or equal) than zero.
Second. The range of the function are the values of

.
Third. If

creases then

always creases, too.
10% of 3.99=0.399x4=1.596
1% of 3.99=0.0399x5=0.1995
1.596+0.1995=1.7955
1.8(Rounded)+3.99=5.79
<em>I</em><em> </em><em>have</em><em> </em><em>attached</em><em> </em><em>the</em><em> </em><em>graph</em><em>!</em><em> </em>

Here are some details about the equation and the graph!
Details of equation ⤵️
- <u>The</u><u> </u><u>equation</u><u> </u><u>is</u><u> </u><u>written</u><u> </u><u>in</u><u> </u><u>slope-intercept</u><u> </u><u>form</u><u>.</u>
- <u>The</u><u> </u><u>slope</u><u> </u><u>of</u><u> </u><u>the</u><u> </u><u>line</u><u> </u><u>is</u><u> </u><u>0</u><u>.</u><u>5</u><u>.</u>
- <u>The</u><u> </u><u>y-intercept</u><u> </u><u>is</u><u> </u><u>1</u><u>.</u>
Details of graph ⤵️
- <u>Root</u><u> </u><u>=</u><u> </u><u>(</u><u>2</u><u>,</u><u>0</u><u>)</u>
- <u>Domain</u><u> </u><u>=</u><u> </u><u>x</u><u>∈</u><u>R</u>
- <u>Range</u><u> </u><u>=</u><u> </u><u>y</u><u>∈</u><u>R</u>
- <u>Vertical</u><u> </u><u>intercept</u><u> </u><u>=</u><u> </u><u>(</u><u>0</u><u>,</u><u>1</u><u>)</u>