(8х+91):7=21
8х+91=21*7
8х+91=147
8х=147-91
8х=56
х=56/8
х=7
5(11x-31)-9x=121
55х-155-9х=121
55х-9х=121+155
46х=276
х=276/46
х=6
(8х+91):7=21
8х+91=21*7
8х+91=147
8х=147-91
8х=56
х=56/8
х=7
5(11x-31)-9x=121
55х-155-9х=121
55х-9х=121+155
46х=276
х=276/46
х=6