Example: 6/20 - 1/5 First, you need to find out what the least common denominator (lcd) is. The lcd is 20 because 20 x 1=20 and 4 x 5 = 20 So ... 6/20 = 6/20 and 1/5 = 4/20 then you take the new fractions and subtract them 6/20 - 4/20 = 2/20 Lastly, if possible you simplify 2/20 =1/10 Hope this helps! I tried to make it as least confusing as possible.