Answer :

So first, we need to convert all of these to the same unit. I am going to use decimals, but any one used works
So, 1/2 is the same as .5
30% is the same as .3
We already know .4
So, the order is .3,.4,.5
Simply replace the decimals with the original numbers and you get:
30%, .4, 1/2

Hope this helped!! :D
30%--> 0.3
1/2-->.5
.4-->0.4 
Least to greatest-->1/2,0.4,30%