#### Answer

$72 m^2$

#### Work Step by Step

The area of a rectangle can be calculated as:
$T=a\times b$
The area of this figure can be calculated as:
Area of the big rectangle (with sides of $3+9$ and $8+4$) minus the area of the small rectangle (with sides of 8 and 9):
$T=(8+4)\times(9+3)-(8\times9)=12^2-72=144-72=72 m^2$