Then 360°/b = the daily motion of the earth,
And 360°/x = the daily motion of the planet,
And 360°/x - 360°/b = the daily gain of the planet:
Also 360°/a = the daily gain of the planet:
Hence 360°/x - 360°/b = 360°/a.
Dividing by 360°, we have 1/x - 1/b = 1/a;
Clearing of fractions, we have ab - ax = bx:
Transposing and collecting, we have (a + b)x = ab:
Therefore x = ab/a+b.
130. The Relative Distance of an Inferior Planet.—By the relative distance of a planet, we mean its distance from the sun compared with the earth's distance from the sun. The relative distance of an inferior planet may be found by the following method:—