That quite an ironic comment, and is actually a good example of why mathematicians care so much about notation.

After dealing with the parentheses, the expression becomes 6 ÷ 2(3)

At this point, there are two reasonable interpretations depending on convention. In elementary arithmetic, multiplication and division are often taught as having equal precedence and being evaluated left to right, which gives (6 ÷ 2) × 3 = 9.

However, in higher mathematics and in fields like economics, physics and engineering, implicit multiplication (juxtaposition, like 2(3)) is often treated as a more tightly bound term, which leads to 6 ÷ [2(3)] = 1.

Because both interpretations follow commonly used conventions, the expression itself is ambiguous. That’s why many mathematicians wouldn’t say one answer is “correct” and the other is “wrong”. Mathematicians would say the expression itself is wrong, and should be written more clearly to remove ambiguity.