Adding a multiplier to the cooler

[OceanOv]

For example: one cooler (outlet) can max 1800 rpm + has a pressure of 30, and the other cooler (inlet) has 2600 rpm and has a pressure of 40. It is necessary to balance the pressure inside the case to rid it of dust and noise caused by resistance.
I would like to have a function not just to add or subtract a percentage (as it is now, for example: +10% or -10%), but 100% of the cooler multiplied by a multiplier ("curve value" * 0.7 or, for example, 1.3).
Thank you!