Consider the function $m(x)=d(5^x+5^f)$, where $d$ and $f$ are positive integers with $d<f$.
Let $u(x)=d(5^x+w)$ and $v(x)=d(5^x)+s$ for appropriate constants $w$ and $s$.
The functions u and v are equivalent to function m.
Which equation expresses the y-coordinate of the y-intercept of $y=m(x)$ as a constant or a coefficient?