а) 5/12+1/3 = (5+4)/12=9/12=3/4
б) 11/24+3/8 = (11+9)/24=20/24=5/6
в) 5/6+1/24 = (20+1)/24=21/24=7/8
г) 57/1000+9/10 = (57+900)/1000=957/1000
д) 7/12-1/4 = (7-3)/12=4/12=1/3
е) 22/27-5/9 =(22-15)/27=7/27
ё) 3/10-43/10000 = (3000-43)/10000=2957/10000
ж) 31/100-21/1000= (310-21)/1000=289/1000