Final answer:
The equation with a constant of proportionality equal to 3 is y = 18/6x (option D).
Step-by-step explanation:
The equation with a constant of proportionality equal to 3 is y = 3x. In this equation, the value of y is directly proportional to the value of x, with a constant rate of change of 3.
To determine the constant of proportionality, we can simplify the given equations and compare them to the form y = kx. Let's check each option:
- A) y = 8/5x can be simplified to y = 1.6x, which does not have a constant of proportionality equal to 3.
- B) y = 1/3x can be simplified to y = 0.33x, which does not have a constant of proportionality equal to 3.
- C) y = 1/4x can be simplified to y = 0.25x, which does not have a constant of proportionality equal to 3.
- D) y = 18/6x can be simplified to y = 3x, which has a constant of proportionality equal to 3.
Therefore, the equation with a constant of proportionality equal to 3 is y = 18/6x (option D).