You find the largest number that will go into each and divide each by that number.
5/9 is a lowest term. They share no common factors.
to reduce you you have to find the two numbers lowest common denominator. Then that is the number that is reduced over the number you got.
No.
17/20
The lowest term has already been reduced as far as it will go. It is not possible to reduce it further.
3/5
5/9
2
-2/5
2/5
1/2
if you mean 40/64 then it is 5/8 in its lowest terms
11/40 is in its lowest terms.
14/45 is already a fraction in its lowest terms.
4/9
10/30