)500-(28.5+25.4-120 : 2): 6-(28:14 +420:140).3

Решение:

1. \( 120 : 2 = 60 \)
2. \( 28.5 + 25.4 = 53.9 \)
3. \( 53.9 - 60 = -6.1 \)
4. \( 500 - (-6.1) = 506.1 \)
5. \( 28 : 14 = 2 \)
6. \( 420 : 140 = 3 \)
7. \( 2 + 3 = 5 \)
8. \( 506.1 : 6 = 84.35 \)
9. \( 84.35 - 5 \cdot 3 \)
10. \( 5 \cdot 3 = 15 \)
11. \( 84.35 - 15 = 69.35 \)

Ответ: 69.35