for a triangular prism, that'd be the area of its traigular face times its length, let's notice that this one if we have it sitting on its 3cm side, it has a height of 4 and a base of 3, so
[tex]\stackrel{\textit{area of its triangle}}{\cfrac{1}{2}(3)(4)}\times \stackrel{length}{10}\implies 60[/tex]
