Solve $323.46 + 23.04 - 43.17 - x = 303$

Concept & Strategy This is a straightforward decimal arithmetic problem. The most effective approach is to follow the order of operations by grouping and solving the additions first, then the subtractions, and finally isolating the unknown variable using basic algebraic principles. Step-by-Step Solution * Group the positive numbers on the left side of the equation and sum them: $$323.46 + 23.04 = 346.50$$ * Substitute this sum back into the equation: $$346.50 - 43.17 - x = 303$$ * Perform the subtraction on the left side: $$346.50 - 43.17 = 303.33$$ * Now the equation is simplified to: $$303.33 - x = 303$$ * Rearrange the equation to solve for $x$ by moving $x$ to the right side and 303 to the left side: $$303.33 - 303 = x$$ * Calculate the final difference: $$x = 0.33$$ Exam Strategy & Shortcut Use the Unit Digit or "Decimal Digit" method to bypass full calculations. Look only at the hundredths place of the numbers: $0.06 + 0.04 - 0.07 = 0.10 - 0.07 = 0.03$. This means the final answer for $x$ must end in a $3$. Since the right side of the equation is a whole integer (303.00), the decimal portion of $x$ must be exactly $0.33$ to balance the $303.33$ on the left. This immediately points to option (a) without doing full vertical math. Common Pitfall A common mistake is misaligning the decimal points when doing vertical addition or subtraction, especially when numbers have different amounts of digits before the decimal. Always ensure the decimal points are perfectly stacked. Final Answer Therefore, the correct answer is **0.33**.