how to work out nci

i normally work out nci by adding nci at aquisition and nci% of sub’s post acq profits which is the net movement of net assets from working 2.
but in many past papers, i see that they work out nci by nci% times by the movement of retained earnings?

so i wonder if this is just an alternate method to work out nci so i should be able to get the same answer from both methods but the problem is i dont. both methods gave me different answers