David, age $31,$ and Ellen, age $30,$ are married and will file a joint return.They cannot be claimed as dependents by any other taxpayer.David and Ellen have no children or other dependents.David and Ellen both work and are not full$-$time students. David earned wages of $$12,000$ and Ellen earned wages of $$4,000.$David and Ellen are U$.$S$.$ citizens and have valid Social Security numbers.David and Ellen have investment income of $$300$ in taxable interest.