You have not been paying taxes during the year. You have withholding taken out to cover the tax on your income. Your tax liability is calculated on your total income. The 45,000 is not just taxed by itself in the table. It adds to your total income. You have to look up the TOTAL INCOME in the tax table. Or actually it’s your total income minus the Standard Deduction (or Itemized Deductions) to give you your taxable income.
