**A printing company advertises business
cards for professionals. Five hundred cards cost $9.90, and 1000 cards cost
$11.90. Determine the mathematical model, assuming that any number of cards can
be purchased.**

** f(x)=7.90 + 0.004 x**

** f(x)=9.70 + 4.00 x**

** f(x)=0.004 + 7.90 x**

** f(x)=4.00 + 9.70 x**

**A firm's fixed costs
are $60. Variable costs are $3.50 per unit. **

**1)At what production level
will costs be exactly equal to revenues? **

**2)What will profit equal?**