Final answer:
The correct mathematical expression for calculating the number of units to earn a target income is the target income divided by the unit contribution margin, option A.
Step-by-step explanation:
The mathematical expression for calculating the number of units needed to earn a target income is found by taking the Target Income and dividing it by the Unit Contribution Margin.
The reason for this is because the contribution margin represents the amount by which the selling price of a unit exceeds the variable costs associated with that unit. By dividing the target income by this amount, we can calculate how many units must be sold to cover both the variable costs and to achieve the desired income above these costs.
For example, if a company has a target income of $10,000 and a unit contribution margin of $25, the number of units needed to meet the target income would be $10,000 divided by $25, which equals 400 units.
Therefore, the correct option for the mathematical expression is A) Target Income divided by Unit Contribution Margin.