Dalto Corporation is located in a state that taxes corporations at $4\%$ of the first $$50,000$ of taxable income plus $7\%$ of any taxable income above $$50,000.$ Corporate income taxes paid to a state are deductible in determining a corporation's federal income tax liability. The corporate federal income tax rate is a flat $21\%$ of corporate taxable income. Dalto earned $$250,000$ of income that is taxable by both the state and federal governments.

Required:

a$.$ Determine Dalto's state income tax obligation.

b$.$ Determine Dalto's federal income tax obligation.

c$.$ Determine the combined $($federal and state$)$ income tax total that Dalto has to pay.

d$.$ If Dalto were to add a new product line that increased its taxable income by $$10,000,$ how much extra income tax $($state plus federal$)$ would Dalto have to pay?

e$.$ What is the appropriate combined marginal tax rate that Dalto should use to evaluate new projects that would increase its taxable income?