Suppose y varies directly as x. If y = 7 when x = 28, what is the value of x when y = 3?

Since y varies directly as x, the ratio y/x stays constant. From y = 7 when x = 28, the constant is 7/28 = 1/4, so y = x/4. When y = 3, x/4 = 3, giving x = 12; the correct choice is 12.

AI-written and checked against the verified answer.