Answer
$\frac{j}{f} = \frac{f}{h}$
Work Step by Step
All three triangles are similar to one another, meaning that the sides of the triangles are proportional.
We can see that $f$ is the longer leg of the large triangle. Additionally, $f$ is the hypotenuse of one of the triangles formed by the altitude of the large triangle. What we want is the hypotenuse of the larger triangle, which is represented by $j$, and the corresponding longer leg of the smaller triangle, which is represented by $h$.
The proportion should read:
$\frac{j}{f} = \frac{f}{h}$
