1/2+1/5+3/7; 1/2+1/5+3/7; 1/2+2/3+3/5; 2/3+1/4+1/5
=(35+14+30)/70=74/70=1 4/70 = тот же пример =(15+10+6)/30=31/30=1 1/30 =(40+15+12)/60=62/60=1 2/60