How do you create an equation or mathematical model from a coordinate table?

Ive been trying to figure this out for days now and still cant get it, and yes its homework but my teachers been sick and its been a pain doing this solo. the table consists of the following; x-coordinates: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. The y-coordinates: 57.9, 108.2, 149.6, 227.9, T, 778.3, 1249, 2871, 4504, 5914. Now the Y-coordinates are the avg orbital radius in mill of km, the problem is that each X-coordinate is a planet from the sun in order starting with Mercury and ending with Pluto. So how would i be able to find an equation for this? I don’t need the answer at all but just how to get there, just graphing it and getting a rough slope line didn’t work, unless i did it wrong XD (ugh). Would i need to consider other things besides the given stats? (Ugh… Math and Science shouldnt collide as much as it does)