Use the formula for the volume of a triangular prism:
[tex]\sf V=\dfrac{1}{2}ach[/tex]
Where 'a' is the triangular base base, 'c' is the triangular base height, and 'h' is the height.
Plug in what we know:
[tex]\sf 60=\dfrac{1}{2}(6)(4)h[/tex]
Simplify:
[tex]\sf 60=12h[/tex]
Divide 12 to both sides:
[tex]\sf h=\boxed{\sf 5}[/tex]