What is the formula for gross margin?

A B D E F G . | Gross Margin Job Sales 1 $ 2,400.00 2 $ 5,400.00 3 $ 9,000.00 4 $ 1,450.00 5 $ 2,200.00 6 $ 7,000.00 7 $ 1,700.00 8 $ 1,600.00 9 $ 8,000.00 10 $ 4,100.00 11 $ 3,200.00 12 $ 2,800.00 Direct Direct Applied Total Job Materials Labor Overhead Cost $ 542.00 $ 300.00 $ 871.11 $ 1,713.11 $ 560.00 $ 1,260.00 $3,658.67 $ 5,478.67 $ 322.00 $ 2,500.00 $ 7,259.28 $ 10,081.28 $ 424.00 $ 75.00 $ 217.78 $ 716.78 $ 306.00 $ 340.00 $ 987.26 $ 1,633.26 $ 432.00 $ 1,760.00 $5,110.53 $ 7,302.53 $ 329.00 $ 230.00 $ 667.85 $ 1,226.85 $ 287.00 $ 310.00 $ 900.15 $ 1,497.15 $ 435.00 $ 2,100.00 $ 6,097.79 $ 8,632.79 $ 381.00 $ 840.00 $2,439.12 $ 3,660.12 $ 402.00 $ 600.00 $ 1,742.23 $ 2,744.23 $ 468.00 $ 440.00 $ 1,277.63 $ 2,185.63