I've tried my best to figure this out,but I've failed. Problem 7: “Bob And Dave Are Twins Again.” Bob travels away from his brother Dave with speed 0.8c and Dave stays at rest. After three years, each counting the years by his own onboard clock, Bob come to rest and Dave will accelerate to 0.8c and eventually catch up with Bob. What will be the total elapsed times on each of their clocks when they meet?