A toy company sells $20,000$ children's tricycles per year, for $$180$ per unit. The company is deciding whether to launch a new battery$-$assisted children's tricycle that would sell for $$300$ per unit. It expects to be able to sell $10,000$ new tricycles per year, but that would come at the cost of losing sales of its existing tricycles by $5,000$ units. What are the incremental sales of the new battery$-$assisted tricycle?

Group of answer choices

$$2\mathrm{.}1$ million

$-$$$6$ million

$$3,9$ million

$$3$ million