Lisa, a single taxpayer, has AGI of $26,000, Social Security benefits of $8,000 in 2021. There is one adjustment, tax-exempt interest of $ 4,000, in arriving at her MAGI (modified adjusted gross income). Under the first formula the base amount for single taxpayers is $25,000 and for married filing jointly the base amount is $32,000. How much of Social Security benefits received in 2021is taxable to her?