Have a question related to paid search advertising.

The equestrian campaign had an average cost per click (CPC) of 0.61. The average price of a pair of cowboy boots is $550, with 50% of it being cost. In order to break even (revenue=cost), what percentage of those people clicking on an ad need to purchase a pair of boots? What does this number mean for the campaign?

I figured it would be 275/.61 but what to do after to find the percentage?