Solution:GPUW → GP(W-2)U (add letter at the place second from the right end)
GIPUW → G (G+2)PUW (add letter at the place second from the left)
GIPSUW → GIP(W-4)UW (add letter at the place third from the right)
GIKPSUW→ GI(G+4)PSUW (add letter at the place third from the left)