GH=HI
7y+3 = 3y-5
4y=-8
y=-2
GH=7y+3 = --14 + 3 = -11
HI = 3y-5 = --6-5=-11
But GH+HI=GI
-11 -11 does not equal 9(-2)+7 = -11
-22 does not equal -11
The lengths are negative, which is strange
and you can't set GH=HI and get GH+HI=GI
There's an inconsistency or contradiction in the problem if you copied it correctly.
Unless when it says H is half way between G and I, it means GHI is an equilateral triangle. H is equidistant from G and I, and then GH=HI=GI
But still you're in some strange space where distances are negative. GH can't equal HI, if the distances are positive 7y+3 = 3y-5 only if y = -2 which makes the distances negative