Answer
$
y=\frac{1}{4}\cdot(x-7)^2+3
$
Work Step by Step
We have $(h, k)=(7,3)$, and $y=a(x-7)^2+3$. Solve for $a$
$$
\begin{aligned}
a(3-7)^2+3 & =7 \\
16a & =4 \\
a & =\frac{1}{4}
\end{aligned}
$$ Hence $$
y=\frac{1}{4}\cdot(x-7)^2+3
$$