A relationship is considered proportional if it can be expressed in the form \( y = kx \), where \( k \) is a constant.
In the equation you provided, \( y = -\frac{3}{4}x \), the equation fits this format, where \( k = -\frac{3}{4} \).
Since there is a constant of proportionality (\( k \)) that relates \( y \) to \( x \) without any addition or subtraction, \( y = -\frac{3}{4}x \) represents a proportional relationship.
Keep in mind that since \( k \) is negative, the relationship means that as \( x \) increases, \( y \) decreases (but it is still proportional because of the direct multiplicative relationship).