Answer
(a) $3300+4.50 x$ dollars
(b) $10.50x$ dollars
(c) $6.00x-3300$ dollars
(d) 551 figures.
Work Step by Step
(a) Based on the given conditions, we have $C(x)=3300+4.50 x$ dollars
(b) The revenue is $R(x)=10.50x$ dollars
(c) The profit is $P(x)=R-C=6.00x-3300$ dollars
(d) To earn a profit, we need $P(x)\gt0$, thus $6.00x-3300$ and $x\gt550$ that is more than 550 figures or at least 551 figures.