Correct Answer: A

Rationale: The correct answer is A, $33.59. To find out how much money she would have left, we need to calculate the total spending by adding the amounts spent at the groceries, dry cleaners, and pet store: $101.85 + $21.90 + $42.66 = $166.41. Subtract the total spending from the initial cash amount to determine the remaining cash: $200.00 - $166.41 = $33.59. Choice B, $29.59, is incorrect as it does not accurately reflect the correct calculation. Choices C and D, $25.59 and $21.59 respectively, are also incorrect as they do not consider the correct total spending amount and subtraction from the initial cash.

Correct Answer: A

Rationale: The correct answer is A: 0.09%. To convert 0.0009 to a percentage, move the decimal point four places to the right and add a percentage sign. Therefore, 0.0009 is equal to 0.09%. Choice B (9%) is incorrect as it represents 0.09 without the decimal point adjustment. Choice C (0.01%) is incorrect as it represents 0.0009 with one less zero. Choice D (0.90%) is incorrect as it represents 0.9 not 0.0009.

Correct Answer: A

Rationale: To find the cost of 1 book, divide the total cost by the number of books: $4 / 3 = $1.33 per book. To determine the cost of 6 books, multiply the cost per book by 6: $1.33 * 6 = $8. Therefore, purchasing 6 books will cost $8. Choice B, $12, is incorrect as it incorrectly doubles the cost of 3 books. Choice C, $6, is incorrect as it is half the cost of 3 books. Choice D, $10, is incorrect as it does not accurately calculate the cost of 6 books based on the given information.

Correct Answer: B

Rationale: To determine the percentage of income remaining after spending 15%, subtract the percentage spent from 100% (100% - 15% = 85%). Therefore, Mary has 85% of her income left, which aligns with answer choice B. Choice A (12%) is incorrect because it represents the remaining amount after spending 88% of her income. Choice C (75%) is incorrect as it does not account for the 15% already spent. Choice D (95%) is incorrect as it does not consider the amount spent by Mary.

Correct Answer: C

Rationale: To convert grams to milligrams, you need to multiply by 1000 since there are 1000 milligrams in a gram. So, to convert 63 grams to milligrams, you would calculate 63 * 1000 = 63,000 milligrams. Therefore, the correct answer is 63,000 mg. Choice A (630 mg) is incorrect as it would be the converted value if the original amount was 0.63 grams. Choice B (63 mg) is incorrect as it is the same value as the original grams. Choice D (63,000 mg) is incorrect as it is the same as the correct answer, but with a comma which is not standard when expressing numerical values.