2/11 х + 5/14 = 9/20 х+6/5
2/11х-9/20 х=6/5-5/14
(40-99)/220 х = 59/70
59/220 х = -59/70
х = -59/70 / 59/220 = - (59*220) / (70*59)=-22/7 = - 3 1/7
-21/100 х -15/56 =3/16 +257/ 800 х
257/800 х +21/ 100 х = -15/56 -3/16
(257+168) / 800 х =( -30-21) /112
425/800 х = -51 /112
17/32 х =-51/ 112
х = -51/112 / 17/32 = -6/7