To answer the given above, multiply the whole equation with least common multiple of the denominators which is 5n. Shown below,
(4/5n - 1/5 = 2/5n) x 5n
4 - 1(n) = 2
-n = -2, n = 2
The answer is not among the choices, it could have been letter A except that the constant in A is negative.
