What is the value of x? 4/5x-1/10=3/10?

Please note that in the original problem you have horizontal division symbols:

 4           1         3
--- x  -    = 
 5         10        10

On the other hand, you have typed    4/5x-1/10=3/10.  To avoid ambiguity you must enclose the fractions inside parentheses:

(4/5)x- (1/10) = (3/10).  Otherwise, your reader will not know for sure whether you meant 4 / (5x) or (4/5)x.

After you've typed in these parentheses, your next task is to mult. all the terms of this equation by 10, to remove the fractions.  Result:

8x - 1 = 3, or 8x = 4,   or    x = 1/2   (answer)