Solve the Problem $\mathrm{n}$ Games Can Be Sold in a Month If the Price

Solve the problem.
-A retailer knows that $\mathrm{n}$ games can be sold in a month if the price is $30-0.3 \mathrm{n}$ dollars per game. If he buys each game for $\$ 3$ , and if he wishes to make a profit of at least $\$ 600$ per month on sales of this game, how many games must he sell each month?

A) $25 \leq$ n $\leq 45$
B) $25 \leq n \leq 40$
C) $40 \leq n \leq 90$
D) $40 \leq n \leq 50$