In 2008, $1.00 u.s. bought 8.24 chinese yuan and in 2010 it bought 6.64 chinese yuan. how many u.s. dollars could 1 chinese yuan purchase in 2008 and 2010?
a. 2008: .12 u.s. dollars; 2010: .15 u.s. dollars
b. 2008: 1.2 u.s. dollars; 2010: 1.5 u.s. dollars
c. 2008: .82 u.s. dollars; 2010: .66 u.s. dollars
d. 2008: .15 u.s. dollars; 2010: .11 u.s. dollars