1) 25*x+15*x+17=257 2) 49*x-12*x=317+2865

1) 25*x+15*x+17=257

                               40х=257-17=240

          х=240/40=6

2)                     49*x-12*x=317+2865

37х=3182

                       х=3182/37=86

25х +15х+17=257               49х-12х=317+2865

40х+17=257                       37х=3182

40х=257-17                          х=3182:37

40х=240                                х=86

х=240:40                               49*86-12*86=317+2865

х=6                                        4214-1032=3182

25*6+15*6+17=257                   3182=3182

150+90+17