Hello, jenni_ann_t!
Start in the "inside" and simplify one step at a time:
\(\displaystyle \;\;\;\;\bigg(\left[(\underbrace{10\,+\,8})\,\times\,2\right]\,-\,3\bigg)\,\div\,3\)
. . . . . . . . . \(\displaystyle \downarrow\)
\(\displaystyle \;\;\;=\;\bigg(\left[\underbrace{18\,\times\,2}\right]\,-\,3\bigg)\,\div\,3\)
. . . . . . . . . .\(\displaystyle \downarrow\)
\(\displaystyle \;\;\;\;\;=\;\left(\underbrace{36\,-\,3}\right)\,\div\,3\)
. . . . . . . . . . . \(\displaystyle \downarrow\)
\(\displaystyle \;\;\;\;\:\ \ \ =\;\underbrace{33\,\div\,3}\)
. . . . . . . . . . . . . \(\displaystyle \downarrow\)
\(\displaystyle \;\;\;\;\;\;\;\,\;\;=\; 11\)