Thank you so much for a clear explanation but I have one more question in mind is that now I know that 0.2 is the day I she is not driving but may I know how is 0.2 calculated?like y is ur value 0.2 ?please explain thank you so much:)

because the total prob is 1, and since the prob of her driving is 0.8, prob of her not driving is 1-0.8 which is 0.2
this is also known as the rule of complement for probability.
where P(A) + P(A’) =1
so in this case, treat A as her using the car, and A’ will be her not using the car

Ohh thank u Soo much ur Soo kind!!☺️☺️