What should I quote for a 20pp A5 full colour Magazine


Hello there,
Recently I got asked to give a quote to design and create a
20pp A5 full colour magazine ready for print = Hi-res PDF

Now there will be 10 pages of adverts which will all be supplied via agencies as hi-res .pdf's
And 6 pages will have editorial content which will have already been proof read.
Then that leaves the covers, Front, inside front, inside back and outside back of which I'll be sorting.

What would be a fair rate to charge for this type of job?

Best regards