Correct Answer: A

Rationale: To simplify the expression 5 x 3 · 9 x 4, first perform the multiplications and divisions from left to right: 5 x 3 = 15 and 9 x 4 = 36. So, the expression becomes 15 · 36. When dividing fractions, multiply the first fraction by the reciprocal of the second fraction. Hence, 15 · 36 = 15/36. To simplify the fraction further, find the greatest common divisor, which is 3. Divide both the numerator and denominator by 3 to get the final result: 15/36 = 5/12. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not represent the correct simplification of the given expression.

Correct Answer: A

Rationale: The correct inequality is 30c + 5p ≤ 100. This represents the combinations of ink cartridges (c) and printer paper (p) that Tom may purchase, ensuring the total cost is less than or equal to $100. Choice B is incorrect because the total cost should be less than or equal to $100, not equal to. Choices C and D are also incorrect as they indicate the total cost being greater than $100, which is not the case given Tom's budget limit.

Correct Answer: D

Rationale: To find the sale price after a 30% discount, you need to subtract 30% of the original price from the original price. 30% of $472 is $141.60. Subtracting this discount from the original price gives $472 - $141.60 = $330.40, which is the sale price Gordon paid. Choice A, $141.60, is incorrect as it represents only the discount amount, not the final sale price. Choices B and C are also incorrect as they do not account for the correct calculations of the discount and final sale price.

Correct Answer: B

Rationale: To find out how many tanks of gas Robert needs for the 1,800-mile trip, first, we calculate the distance his car can travel on a full tank: 30 miles per gallon 12 gallons = 360 miles per tank. Next, divide the total trip distance by the distance per tank: 1,800 miles · 360 miles per tank = 5 tanks. Therefore, Robert will need 5 tanks of gas to complete the cross-country trip. Choices A, C, and D are incorrect as they do not accurately calculate the number of tanks needed based on the given information.

Correct Answer: A

Rationale: To simplify the expression 5 x 3 · 9 x 4, first perform the multiplications and divisions from left to right: 5 x 3 = 15 and 9 x 4 = 36. So, the expression becomes 15 · 36. When dividing fractions, multiply the first fraction by the reciprocal of the second fraction. Hence, 15 · 36 = 15/36. To simplify the fraction further, find the greatest common divisor, which is 3. Divide both the numerator and denominator by 3 to get the final result: 15/36 = 5/12. Therefore, the correct answer is A. Choices B, C, and D are incorrect because they do not represent the correct simplification of the given expression.