Three Identical Units of Item Magnesium XP Are Purchased During

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