Answer:
The constant of proportionality in the equation 2y = 2x is 1.
Note that this equation is actually the same as y = x, which is a linear equation with a slope of 1 and a y-intercept of 0. In this case, the coefficient of x (which is 2) is not the constant of proportionality because it does not represent a proportional relationship between x and y. Instead, the constant of proportionality is the ratio of the change in y to the change in x, which is 1.