$832.58 - 242.31 = 779.84 - $ $x$
Aptitude
Decimal Fraction
Difficulty: Medium
Choose an option
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A$179.57$
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B$199.57$
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C$295.05$
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DNone of these
Answer
Correct Answer: $189.57$
Explanation
### Concept & Formula
Rearrange the balancing equation components to construct an explicit linear solution path for the unknown algebraic variable $x$.
$$ a - b = c - x \implies x = c - (a - b) \implies x = c - a + b $$
### Step-by-Step Solution
* Write down the primary mathematical statement:
* $832.58 - 242.31 = 779.84 - x$
* Transpose $-x$ to the left to turn its value positive, moving left terms to the right:
* $x = 779.84 - 832.58 + 242.31$
* Combine terms based on sign conventions:
* $x = (779.84 + 242.31) - 832.58$
* Execute the positive additions:
* $779.84 + 242.31 = 1022.15$
* Subtract the remaining parameter:
* $x = 1022.15 - 832.58 = 189.57$
* Let's inspect choices: (a) $179.57$, (b) $199.57$, (c) $295.05$, (d) None of these. The exact value $189.57$ is absent, choosing (d).
### Exam Strategy & Shortcut
**Fractional Balancing:**
Evaluate decimal parts alone: $.58 - .31 = .27$.
Right-side setup requires: $.84 - \text{decimal part} = .27 \implies \text{decimal part} = .84 - .27 = .57$.
The correct option must end in $.57$, ruling out option (c).
Estimate integer ranges: $832 - 242 = 590$. Now, $779 - x = 590 \implies x = 779 - 590 = 189$. Since $189.57$ isn't explicitly explicitly option (a) or (b), mark "None of these".
### Common Pitfall
Students often compute $832.58 - 242.31 = 590.27$, then incorrectly add it to $779.84$ instead of subtracting it from $779.84$, leading to wildly inaccurate response targets.
### Final Answer
**Therefore, the correct answer is None of these.**