а) 5/7а +3 /14а = 13/14а
при а = 4 целых 2/3 = 13/14*4 2/3=4 1/3
при а= 7/13=13/14*7/13=1/2
б) 3/8у + у - 1/4 = 11/8у-1/4
при у =2 целых 2/3= 11/8*2 2/3=11/8* 8/3-1/4=11/3-1/4=41/12=3 5/12
при у= 4/9; 11/8*4/9-1/4=11/18-1/4=13/36=
в) 13/15m - 3/4m + 1/12m =12/60=1/5m
при m =2 целых 1/2 = 1/5*5/2=1/2
при m=6 целых 1/4 1/5*25/4=5/4=1 1/4
г) 1/3 x + 3/4х - 4/9х =23/36х
при х=1 целая 13/23=23/36*1 13/23= 23/36*36/23=1
при х= 9/46= 13/23*9/46=1/8