A lot of typos in code for "resolving collisions" section

[dbecker215]

Several times you accidentally used ".x/.y" instead of "_x/_y"
There is a ball.position_y that should simply be ball.y

[noooway]

Several times you accidentally used ".x/.y" instead of "_x/_y"
There is a ball.position_y that should simply be ball.y

Indeed. I'll try to fix that.