If a solution containing primarily 25 mg/L trisodium NTA is permissible to come to equilibrium with solid PbCO3 at pH 8.5 in a medium that contains 1.76 x 10-3 M HCO3(-) at equilibrium, define what is the value of the ratio of the concentration of NTA bound with lead to the concentration of unbound NTA, [PbT(-)]/[HT(2-)]?