If '+' represents '$÷$ ', '$÷$ ' represents '-', '-' represents '$\times$ ', and '$\times$ ' represents '+', then what is the value of:
$$30+10÷6-5\times 6$$

Substitute the given operators with their respective real operations:
* $+$ becomes $÷$
* $÷$ becomes $-$
* $-$ becomes $\times$
* $\times$ becomes $+$

The expression is rewritten as:

$$30÷10-6\times 5+6$$

Applying the BODMAS rule:

1. Division: $30÷10=3$
2. Multiplication: $6\times 5=30$
3. Subtraction & Addition: $3-30+6=9-30=-21$