Check the picture below.
[tex]\textit{volume of a pyramid}\\\\ V=\cfrac{Bh}{3} ~~ \begin{cases} B=\stackrel{base's}{area}\\ h=height\\[-0.5em] \hrulefill\\ B=\stackrel{7\times 7}{49}\\ V=82 \end{cases}\implies \begin{array}{llll} 82=\cfrac{49h}{3}\implies 246=49h\implies \cfrac{246}{49}=h \\\\\\ 5.02\approx h \end{array}[/tex]
