Correct Answer: A

Rationale: To find the length of the rectangle, we use the formula: Length = Area / Width. Substituting the values given, Length = 32 in² / 4 in = 8 in. Therefore, the correct answer is A. Choice B (28 in), Choice C (36 in), and Choice D (128 in) are incorrect because they do not correctly calculate the length based on the given width and area of the rectangle.

Correct Answer: B

Rationale: To calculate the percentage increase, subtract the initial value from the final value, then divide by the initial value and multiply by 100. In this case, the calculation is ((1072 - 841) / 841) x 100 ≈ 27%. Therefore, the correct answer is B. Choice A (22%) is incorrect as it does not match the calculated percentage increase. Choice C (127%) is incorrect as it represents an absolute increase, not a percentage increase. Choice D (78%) is incorrect as it is not close to the calculated percentage increase of 27%.

Correct Answer: B

Rationale: To find the sale price after a 15% discount, you calculate 15% of $78, which is $11.70. Subtracting $11.70 from the original price gives $66.30. Since the price is typically rounded, the estimated sale price is $66. Choice A, $12, is too low and does not reflect a 15% discount off $78. Choice C, $22, and choice D, $69, are also incorrect as they do not accurately estimate the sale price after a 15% discount.

Correct Answer: A

Rationale: The phrase 'thrice a number' translates to 3x, and 'twelve less than' means subtracting 12 from it. Therefore, the correct expression is 3x-12. Choice B, '12-3x', represents '12 less than a number thrice,' which is the opposite of the given phrase. Choice C, '3-12x', does not correctly interpret the phrase provided. Choice D, '12x-3', represents 'a number thrice less than twelve,' which is not the same as the original phrase.

Correct Answer: A

Rationale: A common denominator is a shared multiple of the denominators in a set of fractions. It is necessary when adding or subtracting fractions to have a common denominator to ensure that the fractions can be combined accurately. Choice B is incorrect because the common denominator is related to the denominators, not the numerators. Choice C is incorrect because while the common denominator is the same in all fractions being added or subtracted, it is not necessarily a number that is the same in all fractions. Choice D is incorrect because a common denominator is a multiple of the denominators, not a number that divides evenly into both fractions.