Beginning raw materials inventory on $1/1/23$ totaled $$12,000,$ while ending raw materials inventory on $1/31/23$ totaled $$16,000.$ Purchases of raw materials during the month of January totaled $$22,000.$

$($a$.)$ Calculate the cost of raw materials available for use in January.

$($b$.)$ Calculate the cost of raw materials used in production during January.