An amateur toy maker produces dolls and cars. She can make at most 30 total toys in her spare time in a month. She wants to make at least 4 dolls and 4 cars each month but no more than 10 cars. At the local toy store where she sells her toys, she makes a profit of $25 per doll and $16 per car sold. a) How many of each type of toy should be produced to maximize her profit? b) What is the maximum profit?