What does /b/ mean?

What does this quote mean from President Lyndon B. Johnson mean? I'll repay you back?

• What does this quote mean from President Lyndon B. Johnson mean: ‘Surely there is no more difficult nor more important question in the field of civil rights than of opening up a new job opportunities for ***** Americans, helping them to prepare for those opportunities, and assuring them fair treatment at promotion time’

• Answer:

  Whilst Lyndon B. Johnson was president, Negroes did not have the same rights as white people. Seats and schools were separate, and much of the white population looked upon the black population with disdain. Therefore, although Lyndon B. Johnson could legally give black people rights if he could get a bill passed through Congress, or revoke already implemented racist/sectarian legislature, there would still be problems. The hearts and minds of the people would need to be won in order to ensure that black people would actually be respected in public, be given equality in job centers and in the work place. His difficulties in his Great Society Program can be seen in his quotes