Rita's water tank contains 7.8 gallons of water. Rita 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. Wendy will begin draining her water tank at a rate of 0.9 gallon 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​