á) 2 \(\cdot\) (δ-7) = 4 \(\cdot\) (δ-4) - 17;

Решение:

1. \( 2(\delta - 7) = 4(\delta - 4) - 17 \)
2. \( 2\delta - 14 = 4\delta - 16 - 17 \)
3. \( 2\delta - 14 = 4\delta - 33 \)
4. \( -14 + 33 = 4\delta - 2\delta \)
5. \( 19 = 2\delta \)
6. \( \delta = \frac{19}{2} \)
7. \( \delta = 9,5 \)

Ответ: \( \delta = 9,5 \).