Don't understand whats wrong can someone help? thanks

In 2018, Lisa and Fred, a married couple, had taxable income of $304,500. If they were to file separate tax returns, Lisa would have reported taxable income of $126,500 and Fred would have reported taxable income of $178,000. Use Tax Rate Schedule for reference What is the couple's marriage penalty or benefit? (Do not round intermediate calculations.) Answer is complete but not entirely correct Marriage benefit 1,800