[dad911]

Originally Posted by winders

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http://www.ets.org/s/gre/pdf/gre_math_conventions.pdf
Mathematical expressions are to be interpreted with respect to order of operations, which establishes which operations are performed before others in an expression. The order is as follows: parentheses; exponentiation;negation; multiplication and division (from left to right); addition and subtraction (from left to right).
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Originally Posted by winders

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Mathematical convention - AoPSWiki

Mathematicians abide by conventions in order to allow other mathematicians to understand what they write without constantly having to redefine basic terms. (Imagine if every mathematical paper began with an explanation of PEMDAS!)

Math 1010 on-line
By convention, formulas are evaluated in the following sequence:

Exponentiation.
Multiplication and Division.
Addition and Subtraction
In the case of operations of the same level of precedence, evaluation proceeds from left to right......

If these conventions were absolute we would be severely stifled, To prevent this calamity, the conventions can be modified by the use of parentheses: Expressions in parentheses are evaluated first.

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Scott,
The three sites you refer to all state (red print above) that absent of other instruction, as the original problem was presented, equations should be evaluated CONVENTIONALLY. Using these sites as a reference, thank you for clarifying that the correct solution of 48÷2(9+3) = 288