PEMDAS, you can do a quick search on google for images only, there are some nice pictures of it you might like.
we do the grouping first, from innermost to outmost, and peMDAS, we do MD before any AS.
[tex] \bf [11+(20\div 10)]\times 7\implies \stackrel{\mathbb{PEMDAS}}{[11+(\stackrel{\downarrow }{2})]\times 7}\implies [\stackrel{\downarrow }{13}]\times 7\implies 91 [/tex]
