Sapphire sells two products: ordinary laptops and premium laptops. Ordinary laptops are priced at $$600$ each and premium laptops are priced at $$1,155$ each. The variable cost per unit is $$555$ per ordinary laptop and $$1,090$ per premium laptop. Total fixed cost is $$122,500.$ Sapphire's expected sales mix is four ordinary laptops to one premium laptop. Calculate the break$-$even point in units for ordinary laptops.

a$.1,090$ laptops

b$.2,000$ laptops

c$.500$ laptops

d$.420$ laptops