Brownstone Windows is a small company that installs windows. Its cost structure is as follows: Use (a) the equation method and (b) the contribution method to calculate operating income if Brownstone installs 3,400 windows. Use (a) the Equation method to calculate operating income if Brownstone installs 3,400 windows. Begin by determining the formula to calculate the operating income using the equation method. Then, calculate the operating income. (Abbreviation used: FC = Fixed costs, SP = Selling price, VCU = Variable cost per unit, Q= Quantity of units sold.)