Correct Answer: B

Rationale: The opposite of a number is the number that, when added to it, results in zero. In this case, the opposite of -3 is a number that, when added to -3, gives 0. Therefore, the opposite of -3 is 3, as -3 + 3 = 0. Choice A, -6, is incorrect because -3 + (-6) = -9, not zero. Choice C, 0, is the additive inverse of 0, not -3. Choice D, 6, is also incorrect as -3 + 6 = 3, not zero.

Correct Answer: C

Rationale: To add mixed numbers, first add the whole numbers together, then add the fractions. 6 + 8 = 14. For the fractions: 3/4 + 1/6 = (18 + 4) / 24 = 22/24 = 11/12. Therefore, 6 & 3/4 + 8 & 1/6 equals 14 & 11/12. Choice A is incorrect as it does not represent the correct sum. Choice B is incorrect because it does not match the correct result. Choice D is incorrect as it simplifies to 12 & 1/6, not 12 & 3/24.

Correct Answer: A

Rationale: To calculate the total number of newspapers sold each day, add the sales for each language: 25 (English) + 1 (French) + 16 (Korean) + 16 (Japanese) + 22 (Russian) = 80. Multiply this by the number of language varieties (10) to get the total number of newspapers sold: 80 x 10 = 800. Therefore, the kiosk sells 800 newspapers each day, not 368 as erroneously stated. The correct answer is 800 papers.

Correct Answer: D

Rationale: To divide mixed numbers, convert them to improper fractions. 5 & 3/4 = 23/4 and 1/2 = 2/1. So, 23/4 · 2/1 = 23/4 * 1/2 = 23/8 = 2 & 7/8. Therefore, 5 & 3/4 divided by 1/2 reduces to 11 & 1/2. Choices A, B, and C are incorrect because they do not represent the correct result of dividing 5 & 3/4 by 1/2.

Correct Answer: B

Rationale: To solve the proportion 0.1:10=x:400, first, simplify the left side to 1:100. Then, set up the proportion as 1:100=x:400. Cross multiply to get x = 4. Therefore, the correct answer is B. Choice A (5) is incorrect because it does not match the calculated value of x. Choice C (50) is incorrect as it is not the result of solving the proportion provided. Choice D (25) is incorrect as it does not align with the correct calculation of x.