all you really need to do is multiply your decimal (15.8) by your percent (5) so, you problem would look like 15.8(.05) (note it is .<em>0</em>5 because there need to be 2 decimal places) so, your answer is .79
I can't seem to find the ans to the question you posted and i think that you made a typo. after i modified it a little, it added up so i think this is the answer to your question