My taxable income is $4237 an my tax is $2892. How can this be?

I found a 1099 post filing and went to amend.  In addition, I found that I was not claimed as a dependent on another 1040.  But the resulting tax percent doesn't make sense.  How is a $4,237 taxable income result in a $2,892 due?    something isn't right.  


Please help