Hey there!
So, we would first need to find the area of this prism.
We do 12 x 5 4 1/4
This would give you (264.5)
So, then we would multiply this by 0.25 because each cube is worth that much.
264.5 x .25 would give us 66.125.
66.125 would be your correct answer.
Hope this helps you.