John ends up damaging his hearing aids.  He needs to replace both of them.  They cost $2500 each.  Insurance covers 80% of the cost.  How much does he personally have to pay?
The cost of the hearing aids is $2500 * 2 = $<T>multiply(2500, 2)=5000
So insurance covers $5000 * .8 = $<T>multiply(5000, 0.8)=4000.0
That means it cost him $5000 - $4000 = $<T>subtract(5000, 4000)=1000
