Standard Appliances obtains refrigerators for $$1,590$ less $30\%$ and $8\%.$ Standard's overhead is $15\%$ of the selling price of $$1,650.$ A scratched demonstrator unit from their floor display was cleared out for $$1,335.$

a$.$ What is trie regular rate of markup on cost for a demonstrator unit?

$\%$

Round to two decimal places

b$.$ What is the rate of markdown on the demonstrator unit?