The figure is made up of two shapes, a semicircle and a rectangle.

What is the exact perimeter of the figure?

3π+12 mm
6π+18 mm
3π+18 mm
6π+12 mm

Rectangle with 2 sides labeled. 6 millimeter is labeled at the bottom of the reactangle and 3 millimeter is labeled on the left side. A semicircle adjoins the top side of the rectangle. Inside lines are dashed