If "−" means "plus", "×" means "divided by", "÷" means "multiply" and "+" means "subtraction", then calculate the value of the following expression:
25+54×6−20÷10=?

Let's substitute the original mathematical operators with the newly given meanings:
+ becomes −

× becomes ÷

− becomes +

÷ becomes ×

Rewriting the expression:

25−54÷6+20×10
Applying the BODMAS rule:

Division: 54÷6=9

⟹25−9+20×10
Multiplication: 20×10=200

⟹25−9+200
Addition and Subtraction:

⟹225−9=216
Thus, the answer is 216.