Question

subtract by writting the fractions with common denominaters.1/2-3/8

Answer 1

Look for the lowest common multiple:
2: 2 4 6 [8] 10 12 ...
8: [8] 16 24 ...
\[\frac{1}{2} = \frac{4}{8}\]
So you can rewrite your original equation as
\[\frac{4}{8} - \frac{3}{8}\]
which equals
\[\frac{1}{8}\]