so to add or subtract fractions, the bottom number must be the same
so we need to make the bottom numbers the same without changing the fraction itself
exg to change 1/4 to 4/16 you multiply 1/4 by 4/4 (which equals 1) to get 4/16
so we need to find the Least Common Multiple or the smallest number that each can multiply into so
first we find the factors
15=3 times 5
6=2 times 3
we find the numbers in both of them
there is one 2, one 3, and one 5 so 2 times 3 times 5 or 30
the LCM=30
8/15 times 2/2 (or 1)=16/30
1/6 times 5/5 (or 1)=5/30
16/30-6/30=(16-5)/30=11/30