Answer :

separate 75 into two numbers. Lets use 15 and 5. 15 can be reduced into 3 and 5, while 5 cannot be reduced. The remaining numbers you have will be 5, 5, and 3. 
 
                   75
                   /  \
                 15   5
                 / \
                3  5

Like this- . 75 . /. \. . 25. 3 . /. \. . 5. 5. So the factors are- 3x5x5. Hope I helped!