3x = [(6×6) + 540] ÷ 8
To simplify this, you must first multiply what is in the parenthesis.
3x = [(36) + 540] ÷ 8
Now, you have to add what is in the brackets.
3x = 576 ÷ 8
Divide
3x = 72
Divide both sides by 3 to solve for x
x = 24
In the example I gave (it's an original example, I did not copy from anywhere), the 36 and 540 are added together before being divided by 8. If the brackets were not there, 540 would have been divided by 8 and then added to 36 because of pemdas, which would have given us a completely different answer.
Let me know if you have any questions about this!