Can someone calculate this for me ?

15*3=45
5*2=10
12*2=24
13*2=26
10+45+24+26=105

The net on the left is correct.
surface area is the sum of all side areas.

15*5 = 75
5*12 = 60
15*12 = 180
15*13 = 195

75 + 60 + 180 + 195 = 510

There would be 36.35 pounds