Another factor is- do they move tables and chairs, or do you- or clean around them? Either way, get it in writing before giving a price, because this affects your time on the job.
If you move tables and chairs, how far to move them to be efficient?
My answer to this is- only their own width plus 1 foot for overlap. Not all to one end, then clean half, move them to the other end, clean the second half, then back in their original position. That is very inefficient.
If the tables are on legs, first vacuum the aisles, then move tables with chairs into the aisles, vac and clean where the tables sit, replace the tables, and tab the legs.
If the tables have a solid round base, don't move the tables, just the chairs. There will be nothing under the solid round base.
As to price, that can only be your decision. Ask them what they have been paying, then decide whether you can do it for the same, less, or more.
Gary