решить уравнение
| 8x – 3 | = 21

|8x-3| = 21,
8x-3 = 21 или 8x-3 = -21;
1) 8x-3 = 21;  8x = 21+3 = 24; x = 24/8 = 3.
2) 8x-3 = -21; 8x = -21+3 = -18; x = -18/8 = -9/4 = -(9*25)/100 =
= -(180+45)/100 = -225/100 = -2,25.
Ответ. {-2,25; 3}