The horizontal asymptote of an exponential decay function of the form \( y = a(b^x) \) (where \( 0 < b < 1 \)) is determined by its behavior as \( x \) approaches infinity. For the function you've provided:
\[ y = 3(0.75)^x \]
As \( x \) approaches infinity, the term \( (0.75)^x \) approaches 0. Therefore, the value of \( y \) will approach 0.
Thus, the horizontal asymptote is at \( y = 0 \).
So, the answer is:
The horizontal asymptote is at y = 0.