It is already in its simplest form as 21/169
Well, honey, 169 over 1000 in simplest form is 169/1000. Can't simplify it any further unless you want to get real fancy and turn it into a decimal. But why bother when you've got a perfectly good fraction right there?
144/169
315/169 is the simplest form.
169/200 is in its simplest form.
39/169 = 3/13
idkkk
13 over 18
9/13
42/169
4/13
It is 1/13