Chen makes and sells cups of coffee from a market stall. The coffee is sold for 2.20 per cup. The only fixed cost is the stall rental, which is 50 a day. The variable costs of producing and selling one cup of coffee are 1.25. Chen expects to make and sell 100 cups of coffee per day. What is the margin of safety?

a)47%

b)48%

c)60%

d)77%