Example: Linda buys pencils for her office supply store every month. A case of pencils has a cost, ?, and she purchases ? cases every month. She uses this information to find the total cost, ?, of pencils each month

Example: Linda buys pencils for her office supply store every month. A case of pencils has a cost, ?, and she purchases ? cases every month. She uses this information to find the total cost, ?, of pencils each month. Write the equation for this proportional relationship. Solution: ? = ??.