Simplify the expression. What is the value of x? (5/4)x = 20

Correct Answer: D

Rationale: To solve for x, multiply both sides by the reciprocal of 5/4 to isolate x. (4/5)(5/4)x = (4/5)20; x = 16. Therefore, the correct answer is 32. Choice A (8), Choice B (16), and Choice C (24) are incorrect as they do not represent the correct value of x obtained after correctly simplifying the expression.

Correct Answer: B

Rationale: To find the area of a triangle, you use the formula A = 1/2 base height. Substituting the given values: A = 1/2 10 cm 7 cm = 35 cm². Therefore, the correct answer is B. Choice A (70 cm²) is incorrect as it seems to be the product of the base and height rather than the area formula. Choice C (140 cm²) is incorrect as it appears to be twice the correct answer, possibly a result of a miscalculation. Choice D (100 cm²) is incorrect as it does not reflect the correct calculation based on the given base and height values.

Correct Answer: C

Rationale: To solve the equation 3x + 4 = 19, first, subtract 4 from both sides to isolate the term with x, which gives 3x = 15. Then, divide both sides by 3 to solve for x, resulting in x = 5. Therefore, the correct answer is x = 5. Choice A, x = 3, is incorrect as it does not satisfy the equation. Choice B, x = 4, is also incorrect as it does not make the equation true. Choice D, x = 6, is incorrect as it does not align with the correct solution obtained through the proper algebraic steps.

Correct Answer: A

Rationale: To find the discount amount, calculate 20% of $30: 0.20 $30 = $6. Subtract the discount from the original price to get the sale price: $30 - $6 = $24. Therefore, the correct answer is $24. Choices B, C, and D are incorrect as they do not reflect the correct calculation of applying a 20% discount to the original price of $30.