Gli bought 9 cds.some of them cost $12.75, and the rest cost $11.95. the total was $112.35. how many did he buy at each price?

Let E be the expensive, and C the cheaper.

E+C=9
E(12.75) + C (11.95)=112.35

the answer to your math problem is 6 cds for 12.75 and 3 cds for 11.95