M Studios buys cameras at a unit cost of $140. Their operating expense is 40% per unit of the selling price, and their desired unit operating profit is 25% of the selling price. What is M Studios' rate of mark-up on selling price?

A) 65%
B) 22.75%
C) 75%
D) 25%
E) 60%

Operating Expense

Costs associated with the day-to-day functioning of a business, excluding production costs but including items like rent, utilities, and salaries.

Operating Profit

The profit earned from a firm's core business operations, excluding deductions of taxes and interest.

Mark-up

The amount added to the cost price of goods to cover overhead and profit; typically expressed as a percentage of the cost.