height of vertical post = 6ft
its shadow = 20 in
height of cell phone tower = h ft
shadow = 125 ft = 125*12 = 1500 in
[tex]\large\begin{array}{I} \mathtt{ \dfrac{6~ ft}{20~in}=\dfrac{h~ ft}{1500~in} } \\\\ \mathtt{ h= \dfrac{6~ ft}{20~in} \times 1500~in=450~ft} \end{array}[/tex]
