How do you solve #(10^2-4*8)-:(8+9)#?
Rather than just blindly following PEDMAS/PEMDA/BODMAS etc, just realise that the operations we do with numbers are not equally strong. The strongest operations are done first.
Powers and roots have the biggest effect on a number and are thetherefore the strongest, then comes multiplication and division, and the weakest operations are addition and subtraction.
If a weaker operation must be done first, parentheses are used to show this.
Always count the number of terms first. Each term must simplify to a single answer and these are added or subtracted in the LAST step.
Note that they can be done at the same time because they are independent from each other.