66. A task is to be completed by two people, A and B, who can finish it exactly within the original planned time. If A's efficiency increases by $\frac{1}{3}$, the task can be completed in $\frac{5}{6}$ of the original planned time; if B's efficiency decreases by $\frac{1}{4}$, it will take an additional 75 minutes to complete. The original planned time to complete this task is $\qquad$ hours.