Question

1/2x=1/x+3

Answer 1

If you mean

1/(2x) = (1/x)+ 3 , then
-1/(2x) = 3, and
x = -1/6 ;
however, depending upon where you put the parentheses in your question, other answers are possible.

For example, is 1/x+3 supposed to be 1/(x+3)? Is 1/2x supposed to be
(1/2)x = x/2?