A firm employed 480 workers. After it hired 120 more, all of them women, women made up 40% of the workforce. How many women did the firm employ before this hiring?

After the hiring the workforce is 480 + 120 = 600, of which women are 40% = 240. Since all 120 new workers were women, the firm had 240 - 120 = 120 women before. 240 is the number of women now, not before. 192 is 40% of the OLD strength of 480 - the wrong base, because the 40% describes the new workforce. 360 is the number of men.