3) Вычислим (-2/5)³:
$$\left(-\frac{2}{5}\right)^3 = \left(-\frac{2}{5}\right) \cdot \left(-\frac{2}{5}\right) \cdot \left(-\frac{2}{5}\right) = -\frac{8}{125}$$
Умножим 5 на (-8/125):
$$5 \cdot \left(-\frac{8}{125}\right) = -\frac{40}{125} = -\frac{8}{25} = -0,32$$
Ответ: -0,32