A patient undergoing sinus surgery has a preoperative piggyback of cefazolin ordered. 500 mg of the drug is dissolved in 50 mL of IV solution. The powdered drug was mixed with 10 mL of sterile water before it was added to the IV solution. The drug is ordered to be administered over 20 minutes. The IV tubing delivers 10 drops per mL. The IV should run at ____ per minute.