I am stuck on this problem. Can someone help me understand how to do this?

Suppose a normally distributed set of data has a mean of 185 and a standard deviation of 18. Use the 68-95-99.7 Rule to determine the percent of scores in the data set expected to be below a score of 221. Give your answer as a percent and include as many decimal places as the 68-95-99.7 rule dictates. (For example, enter 99.7 instead of 0.997.)