regex=>lookahead between two matches c#

const string numericReg = "\\d+"; // Matches a digit character. Equivalent to [0-9].
const string realNumsReg = numericReg + b + "(\\." + b + numericReg + ")?";
        const string b = "\\s*";

private const string rte = "(?<rate>" + realNumsReg + ")" +
                          "(?=(?<rte1>" + b + "qs " + "))";

private const string barl = "(?<barl>" + numericReg + ")" +
                                   "(?=((?<q>" + b + "point to print )))";

MatchCollection s = Regex.Matches
                ("3000 qs / min", rte , RegexOptions.IgnoreCase);

MatchCollection s = Regex.Matches
                ("6 point to print  ", barl , RegexOptions.IgnoreCase);

MatchCollection s = Regex.Matches
               ("6 point to print  3000 qs/ min", barl+b+rte  , RegexOptions.IgnoreCase);