The identical twins Speedo and Goslo join a migration from the Earth to Planet X. It is 20.0 light-years away in a reference frame in which both planets are at rest. The twins, of the same age, depart at the same time on dissimilar spacecraft. Speedo's craft travels steadily at 0.880c, Goslo’s at 0.720c. Compute the age difference between the twins after Goslo's spacecraft landson Planet X. Which twin is the older?