(2/5+х)-2/3=4/5

х/90-2/13=8/45

(х-3/14)+2/7=5/6

1)2/5+x-2/3=4/5 6-10/15+x=4/5 -4/15+x=4/5 x=4/5+4/15 x=12+4/15 x=16/15 x=1 1/152)1170•x/90-1170•2/13=1170•8/45 13x-90•2=26•8 13x-180=208 13x=108+180 13x=388 x=388/13 x=29 11/13