Answer:
The width is 10 feet.
Explanation:
We know that the area of a rectangle is given by the formula:
![\displaystyle A=L\cdot W](https://img.qammunity.org/2022/formulas/mathematics/college/nrq4v88yxii0wdkkrmo3taejibbyjj638i.png)
Where L is the length and W is the width.
We are given that the length of the rectangle is three times the width. In other words:
![L=3W](https://img.qammunity.org/2022/formulas/mathematics/college/c4wzjyogy4rcq18t9gw1617m7iwp51jbzz.png)
The total area is 300 square feet. And we want to determine the width of the rectangle.
So, substitute 300 for A and 3W for L:
![(300)=(3W)\cdot W](https://img.qammunity.org/2022/formulas/mathematics/college/he0lzxoy88wdz61kbcy5mrs0473laqaic0.png)
Multiply:
![300=3W^2](https://img.qammunity.org/2022/formulas/mathematics/college/3t7t830jtwhsw1uk3fm1n21s4j24slssce.png)
Divide both sides by three:
![W^2=100](https://img.qammunity.org/2022/formulas/mathematics/college/ydid9wdb2oiixfagg1l0rdbzcht9zutzn2.png)
And take the principal square root of both sides. So:
![W=10](https://img.qammunity.org/2022/formulas/mathematics/college/rbiyipvjewsa2jslq1mt1gpqjnnp16tll3.png)
Thus, the width of the rectangle is 10 feet.