It's the last answer. Think about when you move a point on a graph left 4 spaces it's on the x axis. Because it's going left it's going towards the negative numbers hence minus and not plus. some concept for the y axis.
Answer:
here you go..............
Volume of one cubic block = (1/6)^3 = 1/216 cu ins
Volume of the prism = 1/3 * 2/3 * 2/3 = 4/27 cu ins
Number of blocks to fill prism = 4/27 / 1/216 = (216*4) / 27 = 32