AHLAM has started her own company, AHLAMY SHIRT, which manufactures imprinted shirts of special occasions. Since she has just begun this operation, she rents the equipment from a local printing shop when necessary. The cost of using the equipment is AED $350.$ The materials used in one shirt cost AED $8,$ and AHLAM can sells these for AED $15$ each. a$.$If AHLAM sells $20$ shirts, what will her total revenue be$?$ What will her total variable cost be$?$b$.$How many shirts must AHLAM sell to break even? What is the total revenue for this?