Correct Answer: D

Rationale: To solve the equation 4x - 8 = 16, first, add 8 to both sides to isolate 4x: 4x = 24. Then, divide by 4 to solve for x: x = 6. Therefore, the correct answer is D. Choice A, x = 7, is incorrect as the correct solution is x = 6. Choices B and C are duplicates of choice A and are also incorrect.

Correct Answer: A

Rationale: To find 25% of a number, you multiply the number by 0.25. So, to calculate 25% of 200, you do 0.25 200 = 50. Therefore, the correct answer is A. Choice B (60) is incorrect as it is the result of calculating 30% of 200. Choice C (25) is incorrect as it represents 12.5% of 200. Choice D (30) is incorrect as it is the result of calculating 15% of 200.

Correct Answer: C

Rationale: To convert 9/10 to a decimal, divide 9 by 10: 9 · 10 = 0.9. The correct answer is 0.9. Choice A (0.7) is incorrect as 7/10 is equal to 0.7. Choice B (0.8) is incorrect as 8/10 is equal to 0.8. Choice D (1) is incorrect as 10/10 would be equal to 1.

Correct Answer: C

Rationale: Rationale: - The imaginary unit, denoted as "i," is defined as the square root of -1. - Therefore, 5i can be expressed as 5 times the square root of -1, which is equivalent to 5√-1. - Option A, -5, is a real number and not an imaginary unit multiple. - Option B, i^5, is equal to i because i raised to any power that is a multiple of 4 results in 1, and i^5 is equivalent to i. - Option D, 1/5i, is the reciprocal of 5i and not equivalent to 5i.

Correct Answer: D

Rationale: To find the total number of chapters, divide the total number of pages by the number of pages per chapter: 798 · 6 = 133 chapters. If he reads 2 chapters a day, it will take him 133 · 2 = 66.5 days to finish the book. Therefore, the correct answer is 66.5 days. Choice A is incorrect because it miscalculates the number of days required. Choices B and C are incorrect as they do not consider the correct calculation based on the given information.