Joanne sells silk-screened T-shirts at community festivals and craft fairs. Her marginal cost to produce one T-shirt is $ 4.50 .$4.50. Her total cost to produce 8080 T-shirts is$ 410 comma$410, and she sells them for $99 each.

a. Find the linear cost function for Joanne's T-shirt production.

b. How many T-shirts must she produce and sell in order to break even?

c. How many T-shirts must she produce and sell to make a profit of $500?