Assume that we are manufacturing a product, and assume that the sales price per unit is $70, the variable cost is $20 per unit, and the fixed cost is $85,000; a) how many units would we need to sell to break even? b) How many units would we need to sell to earn a profit of $120,000? c) How many units do we need to sell to double that profit to $240,000? D) Why didn't the number of units double from Part B to Part C?