Can you please help me figure out what to do in this equation and why?
While passing between Earth & Moon, a spacecraft is located on line connecting centers of two bodies and is at a distance of d=102km from radio antenna on surface of Earth. The distance from antenna to the Moon is denoted by dm. Recall that speed of light is 3.0x108 m/s.
How long, in seconds, does it take for signal from spacecraft to arrive at antenna on Earth?