[tex]75|5\\15|5\\.\ 3|3\\.\ 1|\\75=\boxed{5}\cdot\boxed{5}\cdot3\\\\100|5\\.\ 20|5\\.\ \ 4|2\\.\ \ 2|2\\.\ \ 1|\\100=\boxed{5}\cdot\boxed{5}\cdot2\cdot2\\\\175|5\\.\ 35|5\\.\ \ 7|7\\.\ \ 1|\\175=\boxed{5}\cdot\boxed{5}\cdot7\\\\GCF(75;\ 100;\ 175)=\boxed{5}\cdot\boxed{5}=25[/tex]
Answer: 25