Решите уравнения

1. x + 2,6 = 3,4; x = 3,4 - 2,6; x = 0,8 2. x - 4,2 = 6,9; x = 6,9 + 4,2; x = 11,1 3. 63 : (17 - y) = 9; 17 - y = 63 : 9; 17 - y = 7; y = 17 - 7; y = 10 4. 0,3x = 15; x = 15 : 0,3; x = 50 5. 3x - 8 = 15; 3x = 15 + 8; 3x = 23; x = 23/3 = 7 2/3 6. 1/5x + 4 = 2 1/3; 1/5x = 7/3 - 4; 1/5x = 7/3 - 12/3; 1/5x = -5/3; x = -5/3 * 5; x = -25/3 = -8 1/3 7. 6x - 2(4x - 1) = 7; 6x - 8x + 2 = 7; -2x = 7 - 2; -2x = 5; x = -2,5 8. 3(2x + 5) - 2(3x + 1) = 2; 6x + 15 - 6x - 2 = 2; 13 = 2 (решений нет) 9. 0,2x - 0,1(2x - 6) = 0,6; 0,2x - 0,2x + 0,6 = 0,6; 0,6 = 0,6 (x — любое число) 10. 5 1/6 : x = -31; 31/6 : x = -31; 31/6 * 1/x = -31; 1/(6x) = -1; 6x = -1; x = -1/6 11. x - x/8 = 7/16; 7x/8 = 7/16; x = 7/16 * 8/7; x = 1/2 = 0,5 12. x + x/9 = 6; 10x/9 = 6; 10x = 54; x = 5,4