The class party started with five chocolate cakes cut in fourths as shown below in the example.

Explanation:

One large square cake cuts into 4 smaller slices

Since we have 5 such cakes that are cut like this, we have 5*4 = 20 slices all together.

Count the number of dark shaded slices that are shown in the lower diagram. We have 4+3+4+2 = 7+6 = 13 slices of cake that are left over. This must mean the class ate 20-13 = 7 slices.

The fraction of the cakes eaten is 7/20

Notes:

10.4 inches

step-by-step explanation:

2x2x2.6