You can probably use a one-sample proportional test for your data. (Test sample proportion = 20/55 or .36) Find the appropriate table for your critical value at .10 level of significance for a one-tailed test. Compare the test statistic you calculate to the critical value from the table. If the test statistic exceeds the critical value, reject the null. If the test statistic does not exceed the critical value, do not reject the null. You can draw your conclusions from there.
