Substituting 6 for x and 24 for y in y=kx gives 24 = (k)(6), which gives k=4. Hence, y=4x. Therefore, when x = 5, the value of y is (4)(5)=20. None of the other choices for y is correct because y is a function of x, and so there is only one y-value for a given x-value. Choices A, B, and D are incorrect. Choice A is the result of using 6 for y and 5 for x when solving for k. Choice B results from using a value of 3 for k when solving for y. Choice D results from using y=k+x instead of y=kx.