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

Three identical units of merchandise were purchased during May, as follows:?? $$\begin{array} { | c | l | c | r | } \hline & \text { Magnesium XP } & \text { Units } & { \text { Cost } } \\\hline \text { May 3 } & \text { Purchase } & 1 & \$ 130 \\\hline 10 & \text { Purchase } & 1 & 136 \\\hline 19 & \text { Purchase } & \underline { 1 } & \underline { 142 } \\\hline \text { Total } & & \underline { \mathbf { 3 } } & \underline { \mathbf { \$ 4 0 8 } } \\\hline\end{array}$$ 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.