Backers of Equality Amendment Making Illinois a Prime Target
3d in series on ERA examines difficulties proponents face in III; notes proponents of ERA see Cook County high on list of obstacles to ratification; notes pol supporters in county; says despite reluctance of many legislators to take stand on what they consider controversial issue in their dists, ERA has in last 6 yrs frequently had majority support in both houses, and its supporters are convinced it does today; notes Carter's stand; illus (L)