6 × 1,000 = 6,000
2 × 10 = 20
3 × 1/10 = 3/10 = 0.3
5 × 1/1,000 = 5/1,000 = 0.005
6 × 1,000 + 2 × 10 + 3 × 1/10 + 5 × 1/1,000 = 6,020.305
The question is asking you to come up with a real-life example of something that can be represented as 15+ c= 17.50. If I were you I would do sales tax. You bought an item with a 15 dollar price tag, but when you go to check out 2.50 are added in tax to equal 17.50. to solve subtract 15 from 17.50: c= 2.50. Your variable (c) represents the sales tax. Hope that helps! :)