Let the number of cases solved in 2003 be $x$. This was 80% of the number of cases, so there were 5x/4 cases to solve in 2003. So the number of cases to solve in 2004 was $5x/4\times 6/5$, which is $3x/2$. Inspector Remorse solved 60% of the cases, which is 9x/10. So there was a 10% decrease in the number of cases solved.