55. Ruben earned a salary of $60,000 in 2001 and $80,000 in 2006. The consumer price index was 177 in 2001 and 221.25 in 2006. Ruben's 2001 salary in 2006 dollars is

a.$75,000; thus, Ruben's purchasing power increased between 2001 and 2006.

b.$75,000; thus, Ruben's purchasing power decreased between 2001 and 2006.

c.$85,000; thus, Ruben's purchasing power increased between 2001 and 2006.

d.$85,000; thus, Ruben's purchasing power decreased between 2001 and 2006.

Please explain why the answer is a. Thank you.