One crew can seal a parking lot in 12 hours and another in 16 hours. How long will it take to seal the parking lot if the two crews work together?
hr
1/x = 1/12 + 1/16
1/x = 7/48
x = 48/7 = 6 6/7 hours
hr
1/x = 7/48
x = 48/7 = 6 6/7 hours