1/Time = 1/Rate1 + 1/Rate2
In this case, the rates are the individual washing rates of Alan and Fred. Alan can wash a car in 6 hours, so his rate is 1/6 cars per hour. Fred can wash a car in 8 hours, so his rate is 1/8 cars per hour.
Plugging these rates into the formula, we get:
1/Time = 1/6 + 1/8
1/Time = (4 + 3) / 24
1/Time = 7 / 24
Time = 24 / 7
Time ≈ 3.43 hours
Therefore, it would take Alan and Fred approximately 3.43 hours to wash a car together.
