To solve this problem it is necessary to simply apply the concepts related to cross-multiply and proportion between units.
Let's start first by relating the amount of dose needed to be supplied per hour, in other words,
The infusion of 250ml should be supplied at a rate of 75ml / hour, so what amount x of mg hour should be supplied with 50Mg.
Converting to mcg units we know that 1mg is equal to 1000mcg and that 1 hour contains 60 min, therefore
The dose should be distributed per kilogram of the patient so if the patient weighs 72.4kg,
Therefore the client will receive 3.5mcg/kg/min.