If he knows how much the total job should be, then just subtract the estimated amount of cork required and the approximate time it would take for the cork alone. Maybe he doesn't have a good idea how long it would take. My brother happens to own about a dozen companies. One of the most important aspects of doing business is knowing your price per foot of installation and your labor costs from there. My brother's main company has everything down to a science. They do all the takeoffs on the print with electronic pens, which immediately enters data into an estimating program.
Your husband would do well in the future to work on his estimates. It can generate a lot of business if your estimates are tight. He must have some previous job orders with the footage on them. Go from there.
Hope that helps. P.S. He also might want to take into account, the difficulty of the job. If there are a lot of twists and turns, obviously the price should be higher.
