2*x-267=133 287 + (120-x) = 300 300-78:x=287 750+10*х=750

2*x-267=133 300-78:x=287

2*х=133+267 78:х=300-287

2*х=400 78:х=13

х=400:2 х=78:13

х=200 х=6

287 + (120-x) = 300 750+10*х=750

120-x=300-287 10*х=750-750

120-х=13 10*х=0

х=120-13 х=0:10

х=107 х=0