Rita's water tank contains 7.8 gallons of water. She will begin filling her water tank at a rate of 2.1 gallons per minute.

Wendy's water tank contains 97.8 gallons of water. She will begin draining her water tank at a rate of 0.9 gallons per minute.

After how many minutes will both water tanks contain the same amount of water?

A. 25 min
B. 30 min
C. 35 min
D. 75 min