Примеры для 4 класса
 р:121=7000-6871,
с-863=39765:1205,
1206:х=638167-638100,
360:у=190086-189996

р/121=7000-6871р=(7000-6871)*1217000-6871=129р/121=129р=129*121р=1560915609/121=129с-863=39765/1205с=(39765/1205)+86339765/1205=33с-863=33с=863+33с=896896-863=331206/х=638167-638100х=1206/(638167-638100)638167-638100=671206/х=67х=1206/67х=181206/18=67360/у=190086-189996у=360/(190086-18996)190086-189996=90360/у=90у=360/90у=4360/4=90