A selected subject and a standardized scoring system were newly enforced at college entrance examination from 1999. A selected subject system means each student can select one subject in addition to common subject in the field of mathematical research II and a standardized scoring system means we standardize the score of each field as mean 50 and standard deviation 10 in order to adjust the degree of difficulty between fields. In the field of mathematical research II, there may exist not only difference of the degree of difficulty but also that of general studying ability between groups of selected subjects. So when we standardize score, we have to consider them. So far a linear equating which is a parametric method and an equi-percentile equating which is a nonparametric method have been published, but both of them supposed that the general studying ability between groups was equal. So in this paper an adjusted linear and percentile equating method which seems to be adequate to our entrance examination is suggested and is investigated by computer simulation.