Correct Answer: A

Rationale: The correct answer is 'Multiplication.' According to the order of operations (PEMDAS), which stands for Parentheses, Exponents, Multiplication and Division (from left to right), Addition and Subtraction (from left to right), multiplication should be completed first. In the given expression, 3 2 should be solved before adding 6 to the result. This means that the multiplication operation should be prioritized over addition. Choices B, C, and D are incorrect because, in the order of operations, multiplication takes precedence over addition, division, and subtraction, respectively.

Correct Answer: D

Rationale: To convert a decimal to a percent, move the decimal point two places to the right. Therefore, 0.80 written as a percent is 80%. Choice A is incorrect as it represents 40%. Choice B is incorrect as it represents 125%. Choice C is incorrect as it represents 90%.

Correct Answer: B

Rationale: To convert miles per hour to feet per second, you need to convert miles to feet and minutes to seconds. First, convert 72 miles to feet using the conversion factor 1 mile = 5280 feet: 72 miles * 5280 feet/mile = 380160 feet. Then, convert 90 minutes to seconds: 90 minutes * 60 seconds/minute = 5400 seconds. Now, to find the speed in feet per second, divide the distance traveled in feet by the time in seconds: 380160 feet / 5400 seconds = 70.4 feet per second. Therefore, the correct answer is 70.4 feet per second. Choice A, 0.8 feet per second, is incorrect as it is a much lower speed. Choice C, 0.009 feet per second, is also incorrect as it is too low. Choice D, 70.4 feet per second, would be correct if the conversion calculations were accurate, but in this case, it's not the correct answer.

Correct Answer: C

Rationale: To find the fourth person's share, subtract the fractions paid by the first three people from the total bill (1). The first person pays 1/5, the second person pays 1/3, and the third person pays 1/12. Adding these fractions gives 7/15. Subtracting this from 1 gives the fourth person's share as 8/15, which simplifies to 4/5. Therefore, the fourth person pays 4/5 of the bill. Option A (1/4) is incorrect because it does not consider the fractions paid by the first three people. Option B (13/60) is incorrect as it is not the remainder after subtracting the first three fractions from 1. Option D (1/4) is a duplicate of Option A and is also incorrect.

Correct Answer: D

Rationale: The slope of the equation y = 50x is 50, which means that for each additional gigabyte of data used, the cost increases by 50 dollars. Therefore, the interpretation of the slope is that it represents the cost per gigabyte, making '50 dollars per gigabyte' the correct answer. Choices A, B, and C are incorrect because they do not reflect the relationship between the cost and the amount of data used in the given equation.