Please help with this. As I do not understand how to do it.

1. Astrology In 1609 Johannes Kepler discovered two of his three laws that describe the behavior of every planet and two of satellites in our solar system. His third law discovered in 1618, states that the ratio of the squares of the periods of any two moons revolving about a planet is equal to the ratio of the cubes of their average distances from 2 the planet. This can be written as where Ta and To are the periods of the moons and ra and ro are their average distances, from the planets. In 1610 Galileo discovered for moons of Jupiter. The first moon, Io has a period of 1.8 days. Another moon Ganymede has a period of 7.3 days and is 6.5 units further from Jupiter than Io is from Jupiter. Use Kepler's third law to determine the distance of lo and Ganymede from Jupiter 7.3 (xAles