3. [(1/6 + 3) : (a − 2)] · (−4), при a = −5,6

Подставим значение \(a=-5,6\):

\(\left(\dfrac16+3\right):(-5,6-2)\cdot(-4)\).

\(\dfrac16+3=\dfrac{19}{6}\), а \(-5,6-2=-7,6=-\dfrac{38}{5}\).

\(\dfrac{19}{6}:\left(-\dfrac{38}{5}\right)\cdot(-4)=\dfrac{19}{6}\cdot\left(-\dfrac5{38}\right)\cdot(-4)=\dfrac{10}{3}\).

Ответ: \(\dfrac{10}{3}\).