I need some help with this math problem

Step-by-step explanation:
15 long
12 wide
10 high
we need all for walls
hight times length two times ( these are the front and back walls )
hight times width two times ( These are the side walls )
the roof is
width times length (only once as only the ceiling)
same measurement as the floor
can you work it out with that
please mark brainiest