please show detailed calculations

0 Contribution margin; contribution margin ratio Pamcar Industries sell IT equipment, specialising in printers and faxes. The following statement reflects the contribution margin of each activity, and overall profit levels: Printers $3 500 000 2 300 000 1 200 000 400 000 Faxes $1 600 000 1 120 000 480 000 360 000 Total $5 100 000 3 420 000 1 680 000 760 000 Sales Less Variable costs Contribution margin Direct fixed costs Common fixed costs: Utilities Other administration Profit 36 000 162 000 $ 722 000 a. BEP, Multiple products, need to calculate Weighted Average CM b. Estimate required sales units under various alternative changes: make sure how to calculate profit before tax. c. Calculate CM with changes in other variables conditions