the equilivance and half equilivalence point of this titration graph

I need to find the equilivance and half equilivalence point of this titration graph. I need to see how it was found, and I need help identifying the unknown acid that was titrated. It was titrated with a . 9M standardized NaOH Solution, and it was titrated into 20. 00 mL of the unknown acid. The photos are of the data table and the graph if more info is needed let me know