14.8% (percent - per cent meaning "per hundred") becomes 14.8/100 or, to remove the decimal point, 148/1000. You can reduce 148/1000 to 37/250. But why would you want to do that? And yes, 14.8% = 0.148.
Another example: 50% is a percentage and 50/100 is a decimal fraction (the denominator is a power of 10) that can be expressed as 0.5.
To convert a percentage into a decimal fraction simply use use 100 as the denominator (the part below the fraction bar). So 14.8% can be written as 14.8/100. Read more about fractions here: http://bit.ly/d9O4Gr
If you perform the same operation on the nominator and the denominator you get an equivalent fraction. In this case you could - to handle the above fraction more easily - multiply by 10. (14.8*10)/(100*10) = 148/1000.
you asked to reduce the fraction. If you try to reduce 14.8/100 you will find that the nominator and the denominator do not share a factor. This fraction is irreducible. But 148 and 1000 have the gcd of 4 and the resulting fraction would be 37/250. This would be easier to read but more confusing. Nice to know but irrelevant. ;)
The answer is: No, you can not reduce 14.8/100 any more.
For 14.8/100 to become 0.148 type it in your calculator or use the nominator and shift the decimal point by 2 to the left (two 0s in 100 ;) ).