Answer:
13/18 which is 72.22% chance of NOT getting a red sock
Explanation:
As there are 18 total socks, and 13 of them are NOT red, you have a 13 out of 18 chance, or 13/18, or NOT drawing a red sock. This can be converted to the decimal, 0.7222, or percentage of 0.7222 * 100 = 72.22%