Verified Answer :

it can not be more simplified 
but 3m-28/7m can be an option

Answer:  The required simplified form of the given expression is

\(\dfrac{3m-28}{7m}.\)

Step-by-step explanation:  We are given to explain the simplification of the following repression :

\(E=\dfrac{3}{7}-\dfrac{4}{m}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~(i)\)

Since the denominators are different in both the fractions, so we wiill take the L.C.M. of the denominators.

Now, L.CM.(7, m) = 7m.

So, we have from (i) that

\(E\\\\\\=\dfrac{3}{7}-\dfrac{4}{m}\\\\\\=\dfrac{3\times m-4\times7}{7m}\\\\\\=\dfrac{3m-28}{7m}.\)

Thus, the required simplified form of the given expression is

\(\dfrac{3m-28}{7m}.\)