Can someone please explain to me how this question has been solved? Please be simple. Thank you

Question:

There are two actions (Action 1 and Action 2), and two types of possible states (s and t). If Action 1 is taken, there is a 20% chance of state s occurring. If action 2 is taken there is a 50% chance of state s occurring. What are the possible outcomes we need to consider when we want to compare the EV of Action 1 and Action 2?

Solution:

a) Action 1 with state of the world s: 20%

b) Action 1 with state of the world t: 80%

c) Action 2 with state of the world s: 50%

d) Action 2 with state of the world t: 50%

The numbers 50% and 20% are in the question, but can someone explain to me where did 80% come from?