Correct Answer: D

Rationale: When you multiply 2 by 5, the result is 10, not 13. Therefore, the correct answer is 10, which is option D. Choices A, B, and C are incorrect because they do not represent the correct product of multiplying 2 by 5.

Correct Answer: B

Rationale: To determine the tip percentage left, divide the tip amount ($36) by the total bill amount ($200), then multiply the result by 100 to express it as a percentage: (36/200) x 100 = 18%. Therefore, he left an 18% tip on the total bill amount. Choice A (16%) is incorrect because the correct calculation results in 18%. Choice C (20%) and Choice D (22%) are incorrect as they do not match the calculated percentage based on the provided numbers.

Correct Answer: A

Rationale: The Mayan numeric system was a base 20 system, known as vigesimal, as it used base 20 numerals. This system was unique and employed a combination of symbols and positional notation to represent numbers. The Babylonian system was a base 60 system, Roman numerals were based on combinations of letters, and Arabic numerals are in base 10, making choices B, C, and D incorrect.

Correct Answer: A

Rationale: To determine the initial amount she had, we subtract the amount spent ($18) from the total amount she had after spending. If she had $1,070 after spending, subtracting $18 gives us $1,052, which was the initial amount. Choices B, C, and D are incorrect as they do not consider the subtraction of the amount spent to find the initial amount.

Correct Answer: D

Rationale: To convert a fraction to a percentage, you multiply the fraction by 100. To express 4/5 as a percent, you perform the calculation 4/5 * 100 = 80%. Therefore, the correct answer is D, 80%. Choices A, B, and C are incorrect as they do not represent the correct conversion of 4/5 to a percentage.