6) Eli flew home from vacation with a heavy bag. With the first airline he flew, Eli had to pay $29 to check his bag, plus $18 for every kilogram that his bag was over the weight limit. The next
flight was with another airline that had the same weight limit. Eli had to pay $19 per kilogram
that his bag was over the weight limit, in addition to the checked bag fee of $18. By coincidence,
the fees ended up being the same with both airlines. How far over the weight limit was the bag
(x)? How large was each airline's fee (y)?