How do I figure out the probability

There's an equation to calculate out the probability,

Probability : P

Event : E

P (E) = number of outcome favorable to event E / total number of possible outcomes

Here's an example.

There are 4 socks, only 1 is in white color

What is the probability of picking white sock if we choose a sock from the 4 in random?

P (white sock) = 1/4