A documents the details of a functional primitive, which represents a specific set of processing steps and business logic.

The average variable cost of producing a backpack is $15.

The formula for calculating the variable cost per unit using the high/low method is:

where

y₂  : cost at highest level of activity

y₁  : cost at lowest level of activity

x₂  : number of units produced at highest level of activity

x₁  : number of units produced at lowest level of activity

Substituting the values from the question in the formula we get,