XYZ Ltd$.$ is a business specializing in office stationery. They are currently analyzing their notebook manufacturing division. In $2024,$ their notebooks are sold at AED $45$ each. The variable cost to manufacture each notebook is AED $30$ each. Fixed manufacturing costs are AED $15000.$ Other fixed costs are AED $12,000.$ The total sales for the year amounted to AED $90,000.$

a$.$ Estimate the break$-$even point in units for $2024$ 

b$.$ How many notebooks must be sold in $2024$ if the target profit is AED $21000?$

c$.$ What is margin of safety value and percentage