Step-by-step explanation:
The area of this playing field is its width times its length. The length of the field is:
![L=x+3x+2x=6\text{xft}](https://img.qammunity.org/2023/formulas/mathematics/college/isu2xsrgp2tung3d41yidh5h1orlsfyz5l.png)
And its width is 50ft, so the area is:
![A=50ft\cdot6\text{xft}=300\text{xft}^2](https://img.qammunity.org/2023/formulas/mathematics/college/on6m76uj48l3px7tqpkcuk9j26cxtx1epp.png)
And we know that the area is 2100 ft², so we can replace that into the expression above and solve for x:
![\begin{gathered} 2100=300x \\ x=(2100)/(300)=7 \end{gathered}](https://img.qammunity.org/2023/formulas/mathematics/college/ew6n0s2x9yc5b5pvtjea1f77chi9qhmm8y.png)
x = 7
Answer:
The answer is option B. 7