The problem is that most schools or teachers at the primary level will teach the students to remember that the formula for volume is (Length x Breath x Height). However, this is true only if the container is a cube or cuboid (rectangular).
Students should understand that the formula to calculate volume for regular shaped containers is (Base Area x Height). Length x Breath just so happens to be the formula to calculate the area for a rectangle.
This way, the (96 + 80) working by Orckids, which is the combined base area for both containers, would make more sense to students.