7/10-2/10*(1/4+5/6):6целых1/2

7/10-2/10*(6/24+20/24):6целых1/2=7/10-2/10*26/2:13/2=7/10-2/10*26/2*2/13=7/10-2/10*2=7/10-4/10=3/10