how do i compute gross margin?

Required information [The following information applies to the questions displayed below.] The following information pertains to Mason Company for Year 2. Ending inventory consisted of 38 units. Mason sold 412 units at $78 each. All purchases and sales were made with cash. Operating expenses amounted to $3,225. Required a. Compute the gross margin for Mason Company using the following cost flow assumptions: (1) FIFO, (2) LiFO, and (3) weighted average. (Round cost per unit to 3 decimal places and final answers to the nearest whole dollar amount.)