Final answer:
To solve the given equation, the correct value of x is 14/8 or 1.75. A mistake in applying the order of operations can lead to the incorrect answer of 21.
Step-by-step explanation:
To solve the given equation, we need to follow the order of operations (PEMDAS). By simplifying the expression step by step, we find that the correct value of x is 14/8 or 1.75. If a student were to get the answer 21, it indicates a mistake in applying the order of operations. They might have mistakenly added the terms inside the parentheses first, without considering the subtraction and multiplication operations.
Learn more about Order of Operations