Answer
$y=|x-4|+3$.
Work Step by Step
The functions have the form $y=a|x-b|+c$ where $(b,c)$ is the vertex of the function.
Hence, because the vertex is at $(4,3)$, $y=a|x-4|+3$.
Since $(5,4)$ is on the function, plugging in the values we get: $4=a|5-4|+3\\4=a+3\\a=1$.
Thus $y=|x-4|+3$.