Pls pls pls me solve this idk the answer. pls explain how u got your answer and how this works

We have 2  solid figures here and their volume = length*width * height,
So we find the volume of each solid then add them up.
Volume = length*width*height.

Take the small one first 
length = 15,  width = 14 and height = 16
so its volume is 14*15*16 =   3360 

Large solid:

Note that its length =  15 + 16 = 31 

its volume = 31*30*27 =  25,110

So the volume of the whole figure = 25,110 + 3360 =  28,470  (answer).

He will need 2,898 pieces of paper