First we must convert all the values to one mathematical state. We shall convert each to its decimal figure.
a) 0.5 is already a decimal so we leave it alone
b) 1: 5 when simplified makes  1/6  = 0.16
c) 0.35 is already a decimal so we will not touch it.
d) 12/25  = 0.48
e) 4/5 = 0.8
so now we arrange these from the least to greatest:
b, c, a, d, e, 
 now we equate this with the original values so the answer will be:
1:5,  0.35,  0.5,  12/25,  4/5