Correct Answer: B

Rationale: To find the area of a rectangle, you multiply its length by its width. In this case, the length is 5 cm and the width is 4 cm. So, Area = length * width = 5 cm * 4 cm = 20 cm². Therefore, the correct answer is 20 cm². Choice A (9 cm²), Choice C (10 cm²), and Choice D (25 cm²) are incorrect as they do not result from the correct calculation of multiplying the length and width of the rectangle.

Correct Answer: A

Rationale: The correct answer is 'Multiplication.' In the expression 8 + 5 * 3, according to the order of operations (PEMDAS), multiplication should be done before addition. PEMDAS stands for Parentheses, Exponents, Multiplication and Division (from left to right), and Addition and Subtraction (from left to right). Therefore, the multiplication operation should be completed first, making 5 * 3 equal to 15, and then the addition operation should be conducted to get the final result of 8 + 15, which equals 23. Choices B, C, and D are incorrect because in this expression, multiplication takes precedence over addition, division, and subtraction according to the order of operations.

Correct Answer: A

Rationale: To find the number that 20 is equal to 40% of, you can set up the equation: 20 = 0.4 * x, where x is the unknown number. To solve for x, divide both sides of the equation by 0.4. This gives x = 20 / 0.4 = 50. Therefore, 20 is 40% of 50. Choice B, 8, is incorrect because 20 is not equal to 40% of 8. Choice C, 200, is incorrect because 20 is not equal to 40% of 200. Choice D, 5000, is incorrect because 20 is not equal to 40% of 5000. The correct answer is 50.

Correct Answer: D

Rationale: To find the sum of fractions, they need to have a common denominator. In this case, the common denominator is 8. So, 3/4 = 6/8. Adding 6/8 and 5/8 gives 11/8, which simplifies to 1 3/8. Therefore, the correct answer is 1 3/8, which corresponds to choice A. Choices B, C, and D are incorrect as they do not represent the correct sum of 3/4 and 5/8.

Correct Answer: A

Rationale: 18/5 = 3 with a remainder of 3, so it is 3 3/5. 3 1/15 is equivalent to 46/15 which is greater than 18/5 3 1/18 converts to 55/18 which is also greater than 18/5 3 1/54 converts to 163/54