Ok so as we can see, one shape is a circle and the other is a rhombus
The formula for a circle is Pi times radius squared
So, we do Pi times eight squared which is 201 mm squared
Now, for the rhombus, we do side times side
So, we do ,48*24 which is 1152mm squared
BUT we only want the area of the shaded figure, so we minus 1152 by 201 which gives us 951mm squared. Hope this helps :)