560 - 3 х = 278
- 3х = 278 - 560
-3х = -282
3х = 282
х = 282 : 3
х = 94
Проверка:
560 - 3 * 94 = 560 - 282 = 278
278 = 278
2) 8000 : (28m + 4) - 15 = 25
8000 : (28m + 4) = 25 + 15
8000 : (28m + 4) = 40
28m + 4 = 8000 : 40
28m + 4 = 200
28m = 200 - 4
28m = 196
m = 196 : 28
m = 7
Проверка:
8000 : (28 * 7 + 4) - 15 = 8000 : (196 + 4) - 15 =
=8000 : 200 - 15 = 40 - 15 = 25
25 = 25