We are asked to find the perimeter of the figure. To do that we will add the perimeters of the semi-circle and the rectangle.
To determine the perimeter of the semi-circle we will use the following formula:

The diameter is 12 m. Replacing in the formula we get:

Solving the operations:

Now we will find the perimeter of the rectangle by adding the length of all of its sides:

Now, the perimeter of the figure is the sum of the perimeters we found:

Replacing:

Therefore, the perimeter of the figure is 48.28m