I am not sure I follow: maybe I am too old and do net remember math lessons correctly, but for me if airline A offers fare for 100 units and the other airline's fare is 40% lower, I am paying 60 units with the other airlines. Has something changed?
Math hasn’t changed and you are correct about “lower” in your example but:
For 100 units, 40% extra equals 140 units and for 60 units, 40% extra equals 84 units.
If ticket A costs 100 units and ticket B cost 60 units then B costs 40% (paid lower) less than A but A costs 66.667% (pay extra) more than B.