The healthcare provider prescribes ganciclovir 375 mg intravenous (IV) every 12 hour to infuse over 90 minutes. The pharmacy delivers ganciclovir 375 mg in a 150 mL IV bag. How many drops/minute should the nurse regulate the gravity infusion using a drip chamber that delivers 10 drops/mL? (Enter numerical value only. If rounding is required, round to the nearest whole number.)