in 8days Peter can do as much as work as pan can do in 12 days.to do a certain job both together take 36days.in how many days can pan, working alone, complete the job?

90 days

60 days

I think 90 days is the answer.
Assume the first work is of 96 units. therefore Peter does 12 units of work per day and Pan does 8 units of work per day. Both of them together do 20 units of work together per day. Now they take 36 days for this work, hence 36 * 20 = 720 units of the new work.
To do this new work, Pan takes 720 / 8 = 90 Days