if Y=2/4, then it would just be 2/4-1/2. In order to do this problem you would have to find common multiples for the denominators, or just divide 2/4 by 2 making it 1/2. The least common multiple for these two fractions would be 4, so in order to change 1/2 is by multiplying the whole fraction by 2/2 making it 2/4. 2/4-2/4 would just equal 0 :/
