Can we deduct the brick work quantity from the lintel bearing area for calculate the brick work quantity?

If you mean deduct the window opening area from the amount of brick you order... When determining the amount of brick for a job you usually do not subtract window areas and it will contribute to your waste factor. Exceptions are made for large Windows or garage openings. Remember, having extra brick left over will cost you less than running short, stopping the job to wait for one cube to be delivered and bringing your brick man back. You can also run the risk of your last cube not matching and screwing up the apperance of the finished product.