Two Spaceships Approach Each Other Along a Straight Line at a Constant

Short Answer

Two spaceships approach each other along a straight line at a constant relative velocity of
0.9880c as measured by the captain of one of the ships. An observer on Earth is able to
measure the speed of only one of the ships as 0.9000c. From the point of view of the
observer on Earth, what is the speed of the other ship in terms of the speed of light?