Fraternal twins Jack and Jill are sent in two different ships to fetch water from the planet Kusbane that is 20 lightyears away. Jack's ship travels at 0.70 c and Jill's travels at 0.90 c. If the ships depart Earth at the same time, what is the age difference between Jack and Jill when Jack's ship arrives at Kusbane? Which twin is older? Assume that Jill has waited for Jack. (Note: the answer is 4.36 years and Jack is older.