Look above triangle ABC and DEF what is the length of DF?

I thought you said these problems were all different. They look exactly the same to me. 

Figure the volume of one of the small blocks, and use that to divide into the whole volume. 

3 1/4 = 13/4 so the box has a volume of 13/4 * 3 * 1 = 39/4 ft^3 

each small block has a volume of (1/4)^3 = 1/64 ft^3 

(39/4) / (1/64) = 624

Hope this helps love.
-Joker7721

This is the explanation.