Alison made a three-layer gelatin dessert that was 15 cm long by 10 cm wide. The heights of the layers were 3 cm,
2 cm, and 1 cm.

A 3-layer prism. The bottom layer has a length of 15, height of 3, and width of 10. The middle layer has a length of 15, height of 2, and width of 10. The top layer has a length of 15, height of 1, and width of 10.

What is the total volume?

The volume of the bottom layer is cm3.
The volume of the middle layer is cm3.
The volume of the top layer is cm3.
The total volume is cm3.