I had a solution for 9-B which allowed me to not write down an equation.
13337 looks a lot like 11 times something.
13337 - 5 = 11 * 1212 = 13332
13337 + 6 = 11 * 1213 = 13343
13332 is not useful, but luckily, 13343 will suffice.
13343 - 2*14 + 2*11 = 13337 so one valid solution is... umm... negative orange keys. 1215 * 11 + (-2) * 14 = 13337. We need to do better.
50 * 11 *14 = 550*14 = 700*11. We can remove 700 cyan keys and redeem them for 550 orange keys. 515*11 + 548*14 = 13337. Close, but we still have too many cyan keys
We need one more trade, 11*14 = 14*11. 515-14 and 548 + 11. 501*11 + 559*14 = 13337 And there we go!