Estimated Tax Requirement. Zeta Corporation's taxable income for 2019 was $1.1 million, on which Zeta paid federal income taxes of $231,000. Zeta estimates calendar year 2020's taxable income to be $2 million, on which it will owe $420,000 in federal income taxes. a. What are Zeta's minimum quarterly estimated tax payments for 2020 to avoid an un- derpayment penalty? b. When is Zeta's 2020 tax return due? c. When are any remaining taxes due? What amount of taxes are due when Zeta files its return assuming Zeta timely pays estimated tax payments equal to the amount deter- mined in Part a? d. If Zeta obtains an extension to file, when is its tax return due? Will the extension per- mit Zeta to delay making its final tax payments