Sunlight Design Corporation sells glass vases at a wholesale price of$$ $$3\mathrm{.}50$ per unit. The variable cost to manufacture is$$ $$1\mathrm{.}75$ per unit. The monthly fixed costs are$$ $$7,500.$ Its current sales are$27,000$ units per month. If the company wants to increase its operating income by$30\%,$ how many additional units must it$$ sell? $($Round any intermediate calculations to two decimal places and your final answer up to the nearest whole$$ unit.$)$