An observer on Earth sees an alien vessel approach at a speed of 0.60c. Th
yl.ry;y: *b* u2 t*kb.p teti,yv2sdae Enterprise comes to the rescue (Fig.
p2 .y.sy,ytru2** bb a*lt:iyt;e kvd Below), overtaking the aliens while moving directly toward Earth at a speed of 0.90c relative to Earth. What is the relative speed of one vessel as seen by the other? u =
c