(56:3)-2*85

Compute step by step:

• 56:3 means 56/3.
• 2*85 = 170.
• So (56/3) - 170 = 56/3 - 510/3 = (56 - 510)/3 = -454/3.

Final: -454/3, which is -151 1/3 ≈ -151.333...