An 85 usually has a small impact, but it can still lower an A depending on the weight.
Use this calculator to find your exact grade:
Final Grade CalculatorExample 1:
Current grade: 95
Test weight: 30%
Score: 85
→ New grade: ~92
Example 2:
Current grade: 85
Test weight: 30%
Score: 50
→ New grade: ~74.5