Final answer:
The expression 9 x (12 - 7) simplifies to 9 x 5, which is none of the options provided, so the correct answer is 'None of the above'.
Step-by-step explanation:
The expression 9 x (12 - 7) can be simplified by first performing the operation inside the parentheses. According to the order of operations, known as PEMDAS (Parentheses, Exponents, Multiplication and Division, Addition and Subtraction), we solve any expressions inside parentheses first. Thus, we calculate 12 - 7, which equals 5. Now the expression is 9 x 5.
Looking at the given options, none of them directly match 9 x 5. However, by understanding the distributive property of multiplication over addition, we can see that option (d) 9 x (12 + 7) will result in 9 being multiplied by the sum of 12 and 7, which is not equivalent to the original expression. Therefore, the correct answer is not provided in the options available.
Since none of the options match the simplified form 9 x 5, the correct option is:
None of the above.