Risolvi la seguente espressione

$$\left[ \left( \dfrac{5}{4}-\dfrac{3}{2}\cdot \dfrac{1}{3}\right) \cdot \left( \dfrac{17}{21}\cdot \dfrac{7}{34}+\dfrac{1}{2}\right) +\dfrac{1}{2}\right] \cdot \dfrac{7}{4}-\dfrac{3}{4}=$$

$$\left[ \left( \dfrac{5}{4}-\dfrac{1}{2}\right) \cdot \left( \dfrac{1}{6}+\dfrac{1}{2}\right) +\dfrac{1}{2}\right] \cdot \dfrac{7}{4}-\dfrac{3}{4}=$$

$$\left[ \left( \dfrac{5-2}{4}\right) \cdot \left( \dfrac{1+3}{6}\right) +\dfrac{1}{2}\right] \cdot \dfrac{7}{4}-\dfrac{3}{4}=$$

$$\left[ \dfrac{3}{4}\cdot \dfrac{4}{6}+\dfrac{1}{2}\right] \cdot \dfrac{7}{4}-\dfrac{3}{4}=$$

$$\left[ \dfrac{1}{2}+\dfrac{1}{2}\right] \cdot \dfrac{7}{4}-\dfrac{3}{4}=$$

$$\dfrac{7}{4}-\dfrac{3}{4}=$$

$$\dfrac{4}{4}=$$

$$1$$