Final answer:
The constant of proportionality in the equation y = 7x + 2 is 7.
Step-by-step explanation:
The constant of proportionality in the equation y = 7x + 2 is 7. In a linear equation in the form y = mx + b, where m represents the slope and b represents the y-intercept, the constant of proportionality is equal to the slope. In this equation, the coefficient of x is 7, which represents the rate at which y changes with respect to x. Therefore, the constant of proportionality is 7.