Can you help me understand how to solve this problem?

Can you help me understand how to solve this problem? 

According to Catalyst, 15.4% of executive positions in Fortune 500 companies are held by women. Suppose a random sample of 180 Fortune 500 executives is selected.     

(a)      What is the standard error of the proportion?

(b)     What is the probability that, in this sample, more than 20% are women?