1000-200+3-2,5

Compute left to right (same precedence for + and -):

• 1000 − 200 = 800
• 800 + 3 = 803
• 803 − 2,5 = 800,5 (i.e., 800.5)

Answer: 800,5 (or 800.5 in decimal with a dot). If you’re using decimal comma convention, 800,5 is the standard form.