To find the rectangular prisms' volume, we should multiply, each one's width,length and height.
Meaning the formula is : [tex]{ V }_{ rectangular\quad prism }=l\cdot w\cdot h[/tex]
Let's plug the values and then subtract:
[tex]{ V }_{ rectangular\quad prism1 }=25\cdot 13\cdot 7=2275\quad { in }^{ 3 }\\ { V }_{ rectangular\quad prism2 }=14\cdot 11\cdot 9=1386\quad { in }^{ 3 }\\ \\ 2275-1386=\quad 889\quad { in }^{ 3 }[/tex]