How do you subtract 20 mins. 45 seconds from one half hour?

Answer 1

Convert 20 minutes into seconds (20 * 60). There are sixty seconds in a minute. This would make 1200 seconds. Then add the 45 seconds (1245). Convert 30 minutes (1/2 an hour) into seconds (30 * 60). Then subtract 1245 from 1800. This would leave 555 seconds or 9 minutes, 15 seconds. I hope this helps.