Problem $3-25$ Tax Rates $($LO$4)$

Use Table $3\mathrm{.}6.($Do not round intermediate calculations. Enter the average tax rate as a percent rounded to $1$ decimal place.$)$

a$.$ What would be the marginal tax rate for a married couple with income of $$89,600?$

b$.$ What would be the average tax rate for a married couple with income of $$89,600?$

c$.$ What would be the marginal tax rate for an unmarried taxpayer with income of $$89,600?$

d$.$ What would be the average tax rate for an unmarried taxpayer with income of $$89,600?$