This year. Paula and Simon (married filing jointly) estimate that their tax Hability will be $200,000. Last yeor, their total tax liobility was $170,000. They estimate that their tax withholding from their employers will be $175,000 Required: a. Are Paula and Simon required to increase their withholdings or make estimated tax payments this year to avoid the underpayment penalty? b. By how much, if any, must Paulo and Simon increase their withholding and/or estmoted tax payments for the year to avold underpoyment penalties