John takes a 10-minute shower every other day for 4 weeks. If his shower uses 2 gallons of water per minute.  How much water does he use in those 4 weeks?
There are 4*7=<<4*7=28>>28 days in those 4 weeks
That means he takes 28/2=<<28/2=14>>14 showers
So he takes a total of 14*10=<<14*10=140>>140 minutes of showers
So he uses 2*140=<<2*140=280>>280 gallons of water
#### 280