3/12+25/30=15+50 ÷60=65/60=13/10=1 3/10; 10/24-21/54=90-84/216=6/216=1/36; 30/54+22/30=150+198 /270=348/270=58/45=1 13/45; 28 /40-10 /75 =420-80 /75=340/75 =68/15 =4 8/15; 12/27 +14/21=84+126/189 =210/189 =30/27=10/9; 14/24 -15 /40=70-45/120 =25 /120=5/24; итд