They use a system of perpetual inventory. During the six months ended $30$ June $2022,$ the inventory activity was as follows:

Purchases

January commenced business, buying $20$ units at $$5$ per unit

March: $30$ units at $$6$ per unit

May: $35$ units at $$7$ per unit

Sales

Feb: $15$ units at $$10$ per unit

April: $30$ units at $$11$ per unit

June: $30$ units at $$12$ per unit

$1.$ Calculate the COGS for the six months and the closing balance of inventory, assuming:

a$.$ LIFO

b$.$ FIFO

c$.$ Moving average.

$2.$ What is the gross profit for the period, assuming:

a$.$ LIFO?

b$.$ FIFO?

c$.$ Moving average?

$4.$ Compare the effects of LIFO and FIFO on balance sheet valuation of inventory and net profit in periods of:

a$.$ rising prices

b$.$ falling prices.