Given a positive proportional function, when the dependent variable y increases by 3, the independent variable x increases by 9, then the relation of this function is

Given a positive proportional function, when the dependent variable y increases by 3, the independent variable x increases by 9, then the relation of this function is

Let the positive proportional function be y = KX. When the dependent variable y increases by 3 and the independent variable x increases by 9, then y + 3 = K (x + 9)
The solution of the two equations is k = 1 / 3, that is, the positive proportional function is y = 1 / 3x