FDR's New Deal programs often contained equal opportunity clauses stating "no discrimination shall be made on account of race, color or creed",:11 but the true forerunner to affirmative action was the Interior Secretary of the time, Harold L. Ickes. Ickes prohibited discrimination in hiring for Public Works Administration funded projects and oversaw not only the institution of a quota system, where contractors were required to employ a fixed percentage of Black workers, by Robert C. Weaver and Clark Foreman,:12 but also the equal pay of women proposed by Harry Hopkins.:14FDR's largest contribution to affirmative action, however, lay in his Executive Order 8802 which prohibited discrimination in the defense industry or government.:22 The executive order promoted the idea that if taxpayer funds were accepted through a government contract, then all taxpayers should have an equal opportunity to work through the contractor.:23–4 To enforce this idea, Roosevelt created the Fair Employment Practices Committee (FEPC) with the power to investigate hiring practices by government contractors.:22

Answer this question, if possible (if impossible, reply "unanswerable"): The first introduction of a quota system mandated that contractors can't do what?
unanswerable