Iggie took a university teaching job as an assistant professor in 1974 at a salary of $10,000. By 2003, she had been promoted to full professor, with a salary of $50,000. If the price index was 50 in 1974 and 180 in 2003, then what is Iggie's 2003 salary in 1974 dollars?
a. $2,777.78
b. $18,000
c. $26,000
d. $36,000