If '/' means division, then this doesn't make any sense, since division isn't defined for Boolean quantitiesIf A/A'=0, which I am not sure of, I do not think this is correct. then the whole thing cancels out to 0.
Using the logical values of 2,6,10,12,14 and the Quine-McCluskey method, I get ABD' +CD' . Look at your 5th line. B'+A'B = A' + B' , not B'A' .ABC'D' + A'B'CD' + AB'CD' + A'BCD' + ABCD'