600-120+x*6=600
помогите пожалуйста решить)

600-120+х*6=600                1260+2*x=3000
480+6х=600                         1260+2х=3000
6х=600-480                          2х=3000-1260
6х=120                                 2х=1740
х=120:6                                х=1740:2
х=20                                     х=870