Number of pieces Pizza is cut is given as 10.After the party some pizza is left and some consumed .
Amount if pizza consumed in fractions is given as 

The fraction can be reduced to simplest or lowest form by finding the common factor of numerator and denominator .Numerator is 5 and denominator is 10.
Both 5 and 10 can be divided by the common factor 5.
We have 

The fraction can be written as 
 in its lowest form or thei equals 0.5 in decimal .