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The division should be done before multiplying by (2+1) and therefore the calculator with answer 9 is the correct one.

6/2(2+1) = x
6/2(3) = x
3(3) = x
9 = x
--> I used PEMDAS; based on the equation, P (parenthesis first), then if there's Multiplication and Division, you have to solve from left to right... so i this equation, we have to solve the division first, which is 6/2... ^^ then multiple... final answer is 9 ^^

Because the calculator on the right is more advance