δ) 500-(28.5+25.4-120:2): 6-(28:14+420:140)

Решение:

\( 500 - (28.5 + 25.4 - 120 : 2) : 6 - (28 : 14 + 420 : 140) \)

1. \( 120 : 2 = 60 \)
2. \( 28.5 + 25.4 = 53.9 \)
3. \( 53.9 - 60 = -6.1 \)
4. \( -6.1 : 6 \approx -1.01667 \)
5. \( 28 : 14 = 2 \)
6. \( 420 : 140 = 3 \)
7. \( 2 + 3 = 5 \)
8. \( 500 - (-1.01667) = 501.01667 \)
9. \( 501.01667 - 5 = 496.01667 \)

Ответ: 496.01667