I'll guess P is the perimeter, the sum of the edge lengths.
In centimeters
I get 4 + 4 + 4 + 4 for the sides of the isoscles triangles
5 + 5 + 2.8 + 2.8 for the rectangular base
5 for the apex/top
P = 4+4+4+4+5+5+2.8+2.8+5=36.6 cm
Not sure why the exact answer isn't there, but first choice seem best.
Get packing.
