4x+40=6x-40 и ещё 6x-15=4x+5

4x+40=6x-40;                                      6x-15=4x+5; 4x-6x=-40-40;                                     6x-4x=15+5; -2x=-80                                               2x=20; x=-80:(-2)                                           x=20:2; x=40.                                                  x=10. Ответ:x=40.                                        Ответ:х=10.

1)6x-4x=40+40     2x=80     x=80/2     x=40   2)6x-4x=5+15     2x=20     x=20/2     x=10