Correct Answer: A

Rationale: To subtract mixed numbers, find a common denominator. In this case, the common denominator is 20. Convert 15 3/4 to 15 15/20. Then, subtract 15 15/20 - 8 8/20 = 7 7/20. Therefore, the correct answer is A. Choice B is incorrect as it does not match the result of the subtraction. Choice C is incorrect as it is not the result of the subtraction. Choice D is incorrect as it represents the second number being subtracted, not the result of the subtraction.

Correct Answer: B

Rationale: The correct answer is B: 6000 milliliters. There are 1,000 milliliters in a liter. To convert liters to milliliters, you multiply the number of liters by 1,000. Therefore, 6 liters = 6 1,000 = 6,000 milliliters. Choices A, C, and D are incorrect because they do not correctly convert liters to milliliters.

Correct Answer: A

Rationale: The correct subtraction is 12.02 - 9.99 = 2.03. Therefore, the correct answer is A. Choice B, 2.21, is incorrect as it does not result from the given subtraction. Choice C, 3.17, is also incorrect. Choice D, 7.97, is incorrect as well. Thus, A is the only correct answer.

Correct Answer: B

Rationale: To convert a fraction to a decimal, divide the numerator by the denominator. In this case, 1 · 5 = 0.2. Therefore, the correct answer is B. Choice A (0.5) is incorrect because the decimal form of 1/5 is not 0.5. Choice C (1.5) is incorrect as it is the sum of 1 and 0.5, not the decimal form of 1/5. Choice D (0.15) is incorrect as it is the decimal form of 15/100, not 1/5.

Correct Answer: A

Rationale: The correct answer is A: 2.5 liters. There are 1,000 milliliters in a liter. To convert 2,500 milliliters to liters, you need to divide by 1,000: 2,500 / 1,000 = 2.5 liters. Choice B (1.5 liters) is incorrect because it miscalculates the conversion. Choice C (3.5 liters) is incorrect as it overestimates the conversion. Choice D (0.25 liters) is incorrect as it underestimates the conversion. Therefore, the correct conversion is 2.5 liters.