C# Syntax (Toggle Plain Text) 
textBoxEquation.AppendText("()/()");
            this.textBoxEquation.Focus();
 
 
            const string matchNumerator = @"\((?<Numerator>[\d,]*(\.\d*))\)";
            const string matchDenominator = @"\((?<Denominator>[\d,]*(\.\d*))\)";
            const string matchBoth = matchNumerator + @"\/" + matchDenominator;
 
            //const string txtBoxInput = @"()/()";
 
            string txtBoxInput = textBoxEquation.Text;
            System.Text.RegularExpressions.Match m = System.Text.RegularExpressions.Regex.Match(txtBoxInput, matchBoth);
            if (m.Success)
            {
                decimal dNumerator, dDenominator;
                if (decimal.TryParse(m.Groups["Numerator"].Value, out dNumerator) && decimal.TryParse(m.Groups["Denominator"].Value, out dDenominator))
                {
                    //and this right here is your string in latex format
                    string latex = @"\frac {" + dNumerator.ToString() + "}{" + dDenominator.ToString() + "}";
                    decimal valueOut = dNumerator / dDenominator;
                    System.Diagnostics.Debugger.Break();
 
                }
 
            }