I have assumed that the question mark is meant to be forward slash
218-18/2[28-3(2+4)]
Always do brackets first (PEDMAS)
The brackets within the brackets take priority:
218-18/2[28-36]
Now the multiplication inside the brackets:
218-18/2[28-18]
Now the rest of the bracket
218-18/210
Now the division:
218-610
Now the multiplication
36-60
Now the subtraction
-24
Hope this helps :)
