Sparkle Cleaners uses 2/3 of a jug of window cleaner in 3 weeks. How much window cleaner do they use in 1...

Sparkle Cleaners uses 2/3 of a jug of window cleaner in 3 weeks. How much window cleaner do they use in 1 week?
Simplify your answer and write it as a proper fraction, mixed number, or whole number.