Time and Material billing questions

When you guys and gals bill a GC for work done time and material do you show profit and overhead as a separate line item? I once showed a client my worksheet for my bid and the first thing that they zeroed in on was the 15% profit and overhead. They decided to do the job time and material and it cost them 500 more than the bid price. My point is that Profit and overhead has the potential to attract a lot of attention but it is real and should be accounted for. So do you people show it or build it in the other numbers like your hourly rates? Thanks for your time.