First find the total time Carly practices the butterfly stroke in a week: 3 hours/day * 4 days/week = <<3*4=12>>12 hours/week
Then find the total time Carly practices the backstroke stroke in a week: 2 hours/day * 6 days/week = <<2*6=12>>12 hours/week
Then add those two amounts of time to find her total practice time each week: 12 hours/week + 12 hours/week = <<12+12=24>>24 hours/week
Then multiply her weekly practice time by the number of weeks in a month to find her monthly practice time: 24 hours/week * 4 weeks/month = <<24*4=96>>96 hours/month
#### 96