Correct Answer: A

Rationale: To solve the equation, begin by distributing the 3 on the left side: 3x - 12 = 18. Next, add 12 to both sides to isolate x: 3x = 30. Finally, divide by 3 to determine the value of x: x = 10. Therefore, the correct answer is x = 10. Choice B, x = 12, is incorrect as the correct value of x is 10, not 12. Choice C, x = 5, is incorrect as it does not satisfy the equation after substitution. Choice D, x = 3, is incorrect as it does not fulfill the equation when substituted back.

Correct Answer: D

Rationale: Rationale: 1. 7 is divisible by 1 because every number is divisible by 1. 2. 7 is divisible by 7 because any number is divisible by itself. 3. 7 is not divisible by 2 because 7 is an odd number and not divisible by 2. 4. 7 is not divisible by 3 because the sum of the digits of 7 (7) is not divisible by 3. Therefore, 7 is divisible by 1, 7, and itself (7), making the correct answer D) 2, 3, and 7.

Correct Answer: C

Rationale: To calculate the number of mils, first, convert 1.5 grams to milligrams (1.5 grams = 1500 mg). Then, since 1 mil contains 500 mg, divide 1500 mg by 500 mg/mil, resulting in 3 mils required to contain 1.5 grams of substance. Choice A, 9, is incorrect because it miscalculates the conversion. Choice B, 2, is incorrect as it does not consider the correct conversion factor. Choice D, 5, is incorrect as it also miscalculates the conversion.

Correct Answer: B

Rationale: To find x in the proportion 40:5 = 60:x, set up the equation: 40/5 = 60/x. Cross-multiply to solve for x: 40x = 60 * 5 => 40x = 300. Divide by 40 to isolate x: x = 300 / 40 = 7.5. However, x should be a whole number since it represents a quantity, so x = 7. Therefore, the correct answer is 7 (B). Choices A, C, and D are incorrect as they do not satisfy the proportion equation.

Correct Answer: C

Rationale: The temperature increased from 32°F to 145°F, resulting in a total increase of 145°F - 32°F = 113°F. Dividing this total increase by the 4 hours of cooking time gives an average rise of 113°F · 4 = 28.25°F per hour, which can be rounded to 28°F per hour. Therefore, the correct answer is 28. Choice A (20) is incorrect because it does not reflect the actual average rise in temperature per hour. Choice B (32) is incorrect as it does not consider the total temperature increase and divide it by the total hours. Choice D (37°F/hr) is incorrect as it does not match the calculated average rise in temperature per hour.