What is the result of adding 7/21 + 10/21?

Correct Answer: A

Rationale: When adding fractions with the same denominator, you simply add the numerators while keeping the denominator the same. In this case, 7/21 + 10/21 = 17/21. Therefore, the correct answer is A. Choice B (15/21) is incorrect because it adds the numerators incorrectly. Choice C (9/21) is incorrect as it does not reflect the sum of the fractions provided. Choice D (10/21) is also incorrect as it does not represent the correct sum of the two fractions.

Correct Answer: A

Rationale: To add mixed numbers, first convert the fractions to a common denominator. The least common denominator between 8 and 12 is 24. Converting 7 1/8 to 7 3/24 (since 1/8 = 3/24) and 2 4/12 to 2 8/24 (since 4/12 = 8/24), we can add the whole numbers separately to get 9. Then, adding the fractions 3/24 and 8/24 gives 11/24. Therefore, 7 1/8 + 2 4/12 equals 9 11/24. Choice A is correct. Choices B, C, and D are incorrect as they do not reflect the correct addition of mixed numbers with the appropriate conversion of fractions.

Correct Answer: A

Rationale: To subtract mixed numbers, subtract the whole numbers and fractions separately. If necessary, borrow from the whole number when the fraction in the minuend is smaller than the fraction in the subtrahend. The whole numbers are: 25 - 12 = 13. The fractions: 1/7 - 5/7. Since 1/7 is smaller, borrow 1 from 13, making it 12. Then convert 1 whole into 7/7, so the fraction becomes: (7/7 + 1/7) - 5/7 = 8/7 - 5/7 = 3/7. Thus, 25 1/7 - 12 5/7 = 12 3/7.

Correct Answer: A

Rationale: To change a fraction into a ratio, you replace the fraction bar (/) with a colon (:). Therefore, 19/40 as a ratio is written as 19:40. Choice B (40:19) is incorrect as it reverses the order of the numbers. Choice C (19:4) is incorrect as it uses the denominator as the second number, which is not the correct way to represent a ratio. Choice D (40:4) is incorrect as it does not reflect the original fraction accurately.

Correct Answer: A

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.