Net calculation rules need to deduct a different number of hours than paid

We have a requirement where a absence element should pay at the normal rate (hours * rate) but deduct from the accrual plan at 1.5 times the number of hours used. For example, an employee using this leave type who has a pay rate of $10/hr and is absent 5 hours would get paid $50 (5 hours x $10/hr) but should have 7.5 hours (5 hours * 1.5) deducted from their accrual plan.  My attempts so far have tried to manipulate the "hours_passed" value in the fast formula but I either get the correct accrual deduction (7.5) but the wrong