9. 5 workers need to process 735 parts, and in the first 2 days, they have already processed 135 parts. It is known that 1 person took a leave for 1 day during these 2 days. If each worker processes the same number of parts per day, and no one will take leave in the following days, it will take $\qquad$ more days to complete the task.
【Analysis】First find the "unit quantity" $135 \div(5 \times 2-1)=15$, （735-135） $\div 5 \div 15=8$ (days).