It means:
Divide numerator and denominator by the same number as many times as you can
until they no longer have any common factor except '1'.
2/5
1/2
11/40 is in its lowest terms.
14/45 is already a fraction in its lowest terms.
1/7
if you mean 40/64 then it is 5/8 in its lowest terms
154
The lowest term has already been reduced as far as it will go. It is not possible to reduce it further.
That all depends on what you mean by "simplify". Reduce the fraction to the lowest term to get: 1½ If you are referring to "reduce the term to decimal form". Then, we have 1.5.
3/5
5/9
2
-2/5
2/5
1/2
11/40 is in its lowest terms.
14/45 is already a fraction in its lowest terms.