The formula of an area of a trapezoid:
[tex]A=\dfrac{a+b}{2}\cdot h[/tex]
a,b - a baseh - a height
We have:
[tex]a=7\dfrac{1}{2}m=7.5m\\\\b=5.5m\\\\h=5.5m[/tex]
substitute
[tex]A=\dfrac{7.5+5.5}{2}\cdot5.5=\dfrac{13}{2}\cdot5.5=6.5\cdot5.5=35.75\ m^2[/tex]