Three Identical Units of Merchandise Were Purchased During May,as Follows

Three identical units of merchandise were purchased during May,as follows:
$\begin{array}{|l|l|l|c|c}\hline & \text { Magnesium XP } & \text { Units } & \text { Cost } \\\hline \text { May } 3 & \text { Purchase } & 1 & \$ 130 \\\hline 10 & \text { Purchase } & 1 & 136 \\\hline {19} & \text { Purchase } & \underline{1} & \underline{142} \\\hline \text { Total } & & \underline{3} & \underline{\$ 408} \\\hline\end{array}$
Assume that two units are sold on May 23 for $313 total.Determine the gross profit for May and ending inventory on May 31 using a FIFO,b LIFO,and c average cost methods.