$*$E$8\mathrm{.}18($LO$3,5)($FIFO$,$ LIFO, and Average$-$Cost Determination$)$ Keyser Company's record of transactions for the month of April is as follows.

a$.$ Assuming that periodic inventory records are kept, compute the inventory at April $30$ using $(1)$ LIFO and $(2)$ average$-$cost$.$

b$.$ Assuming that perpetual inventory records are kept in both units and dollars, determine the inventory at April $30$ using $(1)$ FIFO and $(2)$ LIFO.

c$.$ Compute cost of goods sold assuming periodic inventory procedures and inventory priced at FIFO.

d$.$ In an inflationary period, which inventory method$-$FIFO, LIFO, or average$-$cost$$will show the highest net income?