If the woman starts out with a salary that we can call X, then is given a pay cut of 10%, her salary will at that point be 0.9X. However, if she is then later given a raise from that salary of 30%, her new salary will be the 0.9X * (1+0.3) = 1.17X. So, in aggregate, she will have seen a 17% increase in her base salary over the period.