The area of a trapezoid is given by:
[tex]A=\frac{b1+b2}{2}\cdot h[/tex]where:
b1 = Long base = 16m
b2 = Short base = 8m
h = Height = 4.5m
so:
[tex]\begin{gathered} A=\frac{16+8}{2}\cdot4.5 \\ A=\frac{24}{2}\cdot4.5 \\ A=12\cdot4.5 \\ A=54m^2 \end{gathered}[/tex]