Given:
Point H is on line segment GI
The length of the line GH = 12.
The length of the line GI = 17.
The objective is to find the length HI.
The unknown length can be calculated as,
[tex]\begin{gathered} GI=GH+HI \\ 17=12+x \\ x=17-12 \\ x=5 \end{gathered}[/tex]Hence, the length of HI is 5.