You need the radius of all the orbits
earth radius is 150 million km
1. 150 million x 10 = 1500 million
From the website below Saturn would be the closest at 1,429 million km
1,500,000,000 - 1,429,000,000 = 71,000,000 km = 7.1 * 10^7 km
I hope this helps :D