4. Margaret, a married taxpayer filing a joint retum, engaged in two business activities this year. Business A eamed $470,000 of profit. Business B incurred a loss of $(995,000). How much of Margaret's net business loss is not currently deductible if the MFJ threshold is $510,000 ? 4. Margaret, a married taxpayer filing a joint retum, engaged in two business activities this year. Business A eamed $470,000 of profit. Business B incurred a loss of $(995,000). How much of Margaret's net business loss is not currently deductible if the MFJ threshold is $510,000