As I learned the "Order of Operation" in Mathematics

It is BODMAS

BODMAS meaning Brackets, Of or Order, Division, Multiplication, Addition and Subtraction.

So the correct answer must be -

7+{7/7}+7x7-7
7+1+{7x7}-7
8+49-7
57-7
=50

So You are absolutely right @diggeri

bravo @diggeri