1) (х + 240) * 3 = 1260
3х + 720 = 1260
3 х = 1260 - 720
3 х = 540
х = 540 : 3
х = 180
_____________
(180 + 240) * 3 = 1260
420 * 3 = 1260
1260 = 1260
Ответ : х = 180
2) х + (240 * 3) = 1260
х + 720 = 1260
х = 1260 - 720
х = 540
______________
540 + (240*3) = 1260
540 + 720 = 1260
1260 = 1260
Ответ: х = 540
3) х + 240 = 1260 * 3
х + 240 = 3780
х = 3780 - 240
х = 3540
_____________
3540 + 240 = 1260 * 3
3780 = 3780
Ответ: х = 3540