Without any indication of how ##x## relates to the right prism this question can not be answered.

Based on the diagram I assume the right prism is a triangular right prism.

In this case if the sides of the triangular surface are ##ab and c##

and the height of the prism is ##h##

then the volume of the prism would be:

##color(white)(XXX)Volume=24m^3=hxxArea_triangle##

##color(white)(XXX)##where ##Area_triangle = sqrt(s(s-a)(s-b)(s-c))## with ##s=(a+b+c)/2##

If ##x## is one of ##a b c h## and the other 3 values are given we could plug the values into this relation to determine the value of ##x##