Answer :
[tex]45|5\\.\ 9|3\\.\ 3|3\\.\ 1|\\45=5\cdot\fbox3\cdot\fbox3\\\\72|2\\36|2\\18|2\\.\ 9|3\\.\ 3|3\\.\ 1|\\72=2\cdot2\cdot2\cdot\fbox3\cdot\fbox3\\\\99|3\\33|3\\11|11\\.\ 1|\\99=\fbox3\cdot\fbox3\cdot11\\\\GCF(45;\ 72;\ 99)=\fbox3\cdot\fbox3=\boxed{\boxed{9}}[/tex]
The factors of 45 are: 1, 3, 5, 9, 15, 45
The factors of 72 are: 1, 2, 3, 4, 6, 8, 9, 12, 18, 24, 36, 72
The factors of 99 are: 1, 3, 9, 11, 33, 99
The common factors are: 1, 3, 9
Hope this helps. :)
