She uses 7 x 2 = <<7*2=14>>14 gallons of water to clean the two cars.
She uses 14 - 11 = <<14-11=3>>3 gallons of water to water the plants.
The total gallons of water that she uses to clean the cars and to water the plants is 14 + 3 = <<14+3=17>>17.
Jan has 65 - 17 = <<65-17=48>>48 gallons of water remaining after cleaning the cars and watering the plants.
Jan uses 48 / 2 = <<48/2=24>>24 gallons of water to wash her plates and clothes.
#### 24