 Multiply a mixed amount's quantities (and total prices, if any) by a constant.
multiplyMixedAmount :: Quantity -> MixedAmount -> MixedAmount
multiplyMixedAmount n = transformMixedAmount (*n)

--
multiplyMixedAmount :: Quantity -> MixedAmount -> MixedAmount
multiplyMixedAmount n = transformMixedAmount (*n)
multiplyMixedAmount n = transformMixedAmount (*n)