u can learn about fractions here
http://www.purplemath.com/modules/fraction.htm
& here
http://www.google.com/search?hl=en&q=fractions
u can do the mixed numbers by timesing the bottoms buy the numbers & then adding
like 2 1/4=4*2+1/4=8+1/4=9/4 then do the plussing or whatever