Answer :
we have
6 ft of a person ----> 4 ft shadow
21 ft of a tree -------> x
[tex]\begin{gathered} \frac{6}{21}=\frac{4}{x} \\ 6\times x=21\times4 \\ 6x=84 \\ \frac{6x}{6}=\frac{84}{6} \\ x=14 \end{gathered}[/tex]answer: B. 14 ft
we have
6 ft of a person ----> 4 ft shadow
21 ft of a tree -------> x
[tex]\begin{gathered} \frac{6}{21}=\frac{4}{x} \\ 6\times x=21\times4 \\ 6x=84 \\ \frac{6x}{6}=\frac{84}{6} \\ x=14 \end{gathered}[/tex]answer: B. 14 ft