At 9:30a.m. Andrew left Exeter for Portsmouth, cycling at 12 mi/h. At 10:00a.m.Stacy left Portsmouth for Exeter, cycling at 16mi/h. The distance from Exeter to portsmouth is 20 mi. Find the time when they meet.
Here's another way to look at it. Andrew has traveled 6 miles when Stacy starts, so together they must cover the remaining 14 miles. Since they are traveling towards each other, you can add their rates and figure out the time it takes.