Correct Answer: D

Rationale: To convert kilograms to grams, you multiply by 1,000 since there are 1,000 grams in a kilogram. Therefore, 8 kilograms = 8 x 1,000 = 8,000 grams. The correct answer is 8,000 grams, which is option D. Choices A and C are incorrect as they incorrectly multiply by 10,000 instead of 1,000. Choice B is incorrect as it divides 8 by 10 instead of multiplying by 1,000.

Correct Answer: D

Rationale: To calculate 75% of 80, you multiply 0.75 by 80, which equals 60. Therefore, the correct answer is 60. Choices A, B, and C are incorrect because they do not represent 75% of 80. Choice A (35) is close to 50% of 80, Choice B (45) is close to 56.25% of 80, and Choice C (70) exceeds 80.

Correct Answer: C

Rationale: To calculate the total number of words typed in 20 minutes, multiply the typing speed per minute (45 words) by the duration in minutes (20 minutes): 45 words/min 20 min = 900 words. Therefore, the correct answer is 900 words. Choices A, B, and D are incorrect because they do not reflect the accurate calculation based on the given information.

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.

Correct Answer: A

Rationale: Subtract the whole numbers and then subtract the fractions: 12 - 7 4\5 = 5 1\5.