Melody $(30$ y$.$o$.)$ and Kenneth $(30$ y$.$o$.)$ Logan plan to file MFJ$.$

a$.$ They plan to claim their son, Jacob $(4$ y$.$o$.)$ and daughter Olivia $(5$ y$.$o$.).$

b$.$ Melody earned a salary of $$42,050($FIT $$0).$

Write out the tax formula to determine the amount of refund or tax due: