5. Упростите выражение: 8x - (3x+\frac{2}{5}) + (5x-\frac{9}{20}).

8x - (3x + \frac{2}{5}) + (5x - \frac{9}{20}) = 8x - 3x - \frac{2}{5} + 5x - \frac{9}{20} = (8x - 3x + 5x) + (-\frac{2}{5} - \frac{9}{20}) = 10x + (-\frac{8}{20} - \frac{9}{20}) = 10x - \frac{17}{20} = 10x - 0,85