These is extra credit, help

Acomputer store bought a program at a cost of $10 and sold it for $13. find the percent markup

Acd that is originally priced at $15.85 red-tagged for the sale. what is the sale price of the cd

Atrain leaves little? rock, arkansas, and travels north at 90 kilometers per hour. another train leaves at the same time and travels south at 80 kilometers per hour. how long will it take before they are 680 kilometers? apart?