Actually, I am pretty sure the left one is correct:

The problem here is the programming in the Calculator. Classic vs Math Print mode
Read more here if interested:
https://en.wikipedia.org/wiki/Order_of_operations

For the actual solving of this problem gotta know:

PEMDAS

Parentheses - Perform Operation Inside Parentheses
Exponent- N/A here
Multiplication/Division - From Left to Right; So where 2(3) does = 6; you have to divide first before multiplying. The way you did it actually has a historical precedent that before 1917 would have been correct (watch here, you need sound for the end, as he explains why):

Addition/Subtraction - N/A as this was done in the parentheses

So steps:

1. 6/2(2+1) = 6/2(3)
2. 6/2(3) = 6/2x3
3. 6/2x3 = 3x3
4. 3x3 = 9