Please give me a detailed explanation such as how can I get that number T.T

NOTE: To incorporate data / calculations from Question 2 when answering Question 3. In addition to the all-you-can-eat buffet, Bottomless Pot is considering offering set-meals for diners in 2021. The costs of food for the set-meals is expected to be $4 per set-meal and the direct fixed costs are $5,000 per month. Besides the costs of food, there are additional variable costs of $7 per diner regardless of whether they ordered buffet or set-meals. Other than the costs of food, Bottomless Pot expects to incur common fixed selling and administrative costs totalling $80,262 per month. It is estimated that 80% of the diners would order the buffet and the remaining diners would order the set-meals. Bottomless Pot charges each diner $50 for the buffet and $30 for the set- meal. Required: (a) Bottomless Pot expects 5,850 diners in January 2021. Calculate January's operating income for buffet, set-meals and the restaurant as a whole. (4 marks) (b) Refer to (a). Calculate the number of diners to break-even per month. (5 marks) (c) Refer to (a). (i) Calculate the margin of safety in sales dollars) for January 2021. (ii) Define "margin of safety". (iii) Explain briefly the significance of Bottomless Pot's margin of safety for January. (7 marks) (d) Bottomless Pot observes that the profit margin for the buffet is much higher than set- meals. It is considering reducing the price of the buffet to $45 per diner; and estimates that with the price reduction, 90% of the diners would order buffet instead of set-meals. (1) Re-calculate the operating income for 5,850 diners. (ii) How much is the change in operating income as compared to (a). Should Bottomless Pot go ahead with this change? Month Number of diners Costs of food $ January February 2,832 4,895 55,900 68,600 March 3,920 59,700 3,840 58,600 April May June 4,150 2,395 July August September October 4,272 3,985 2,520 4,732 2,633 3,935 62,000 54,600 63,300 60,400 53,900 69,900 56.900 51,200 November December