Larry earns $25,000 and pays $2,500 in tax, while Suzy earns $50,000 and pays $15,000 in tax. If Larry's income increases by $100, his tax increases by $12, but if Suzy's income increase by $100, her tax increases by $35. Calculate the average tax rate and marginal tax rate that Larry pays and that Suzy pays. Is this income tax fair? Explain.