Solution

Correct answer is A B + C D * E - * F * G /

Concept:

Precedence Order (highest to lowest) and Associativity (left to right)

() has highest precedence

* and / has same precedence

+ and – has same precedence

(* and /) and higher precedence than (+, -)

Explanation: 

(A + B) * (C * D ‐ E) * F / G 

A B + * (C * D ‐ E) * F / G 

A B + * (C D * ‐ E) * F / G 

A B + * C D * E - * F / G 

A B + C D * E -  * * F / G 

A B + C D * E -  * F * / G

A B + C D * E -  * F * G /

Additional Information: 

You can underline the partially completed postfix conversion to keep track of conversion, and avoid silly mistakes and confusion.