Math questions and topics from the Official Guide and Quantitative Review books. Please try to follow the posting pattern (e.g. OG - DS - #142) to allow for easier searches. Questions posted in the GMAT Math section regarding the OG have been moved here.
1/10 percent of 5000 is .1% of 5000 which is 5 and 1/10 of 5000 is 500.......therefore 500-5=495. I think you are missed the percent part of the question. That is the mistake you are making.
Note that the solution shows the math in the REVERSE order in which it is stated in the sentence. The sentence says the first part "is subtracted from" the second part, so that gets written mathematically as "second part minus first part."