well, firstly, we can divide the shape into three: two semi-circles and a rectangle. secondly, the two semi-circles form a circle, because they have the same R.
well, the area will be founding in this way: the amount of areas of rectangle and a circle.
1) Area of rectangle: ab=3*7=21 mm
2) area of circle: πR^2=3,14*1,5^2=7.065 mm
3) 21+7.065=28.065≈28.07 mm
answer: 28.07 mm