How do i make 60/100 into simplest form

Reduce 60/100.  There are various ways in which you could do this.
One way would be to drop the final zero (0) of both integers:  6/10; and then reduce 6/10 to 3/5 by dividing 6 and 10 each by 2.

Note that 3/5 is still a rational fraction, since it's the ratio of two integers, 3 and 5.