Explanation:

- Let's evaluate the original expression: $8\times 9÷15+30-5$.

- If multiplications and divisions are performed first, it simplifies to: $72÷15+30-5$.

- This results in: $4.8+30-5$.

- Solving further gives: $29.8$, which isn't 63.

- Option 1: Switching '-' and '×'

- Expression becomes: $8-9÷15+30\times 5$.

- This results in: $-0.6+150$, which sums to $149.4$.

- Option 2: Switching '+' and '-'

- Expression becomes: $8\times 9÷15-30+5$.

- This leads to: $4.8-30+5=-20.2$.

- Option 3: Switching '+' and '×'

- Expression becomes: $8+9÷15\times 30-5$.

- This results in: $8+18-5=21$.

- Option 4: Switching '÷' and '-'

- Expression becomes: $8\times 9-15+30÷5$.

- Calculation: $72-15+6=63$.

Correct Answer: Option 4 - '÷' and '-'

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