6.7. Вычислите: 10) −3,5⁻¹ + (−2,5)⁻²;

−3,5⁻¹ = −1/3,5 = −2/7; (−2,5)⁻² = 4/25.

−2/7 + 4/25 = −50/175 + 28/175 = −22/175.

Ответ: −22/175.