15/65
By cancelling down/reduction.
We note, in this case, that both numbers end in '5'.
So '5' is a common factor; 5 x 3 = 15 and 5 x 13 = 65
So cancel down/reduce by '5'
15/65 = 3/13
Since both '3' & '13' are prime numbers this will NOT reduce any further.
Hence
15/65 in its simplest form is 3/13.
NB Any number, however large or small, that ends in '5' or '0' , has '5' as a common factor. Refer to your '5' times multiplication table.
9/15 in its simplest form is 3/5
15/19 is already in its simplest form, because '19' is a prime number, and there are NO factors of '19' except '1' & '19'.
15/7 is in its simplest form.
39/45 can be simplified to 13/15.
8/15 is in its simplest form.
15 over 30 in simplest form is 1/2.
9/15 in its simplest form is 3/5
30/16 in simplest form is 15 over 8
1/7
11/15
It is: 9/15 = 3/5
4 over 15 is already in lowest terms.
2x over 15
15/6 = 5/2 = 2 1/2
12/15 = 4/5
2/15
13/15