What do you get when you use your calculator to divide 84 by 15? What does this tell you about 15 and 84?

The probability that David will eat a healthy breakfast or that it will rain is 0.85 or 85%.

Step-by-step explanation:

Consider the provided information.

There is an 80% chance David will eat a healthy breakfast.

P(H) = 0.8

There is a 25% chance that it will rain.

P(R) = 0.25

The probability of David will eat a healthy breakfast and it will rain is:

P(H ∩ R)  = 0.8 × 0.25 = 0.2

P(H ∪ R) = P(H) + P(R) - P(H ∩ R)

P(H ∪ R) = 0.8 + 0.25 - 0.2

P(H ∪ R) = 0.85

Hence, the probability that David will eat a healthy breakfast or that it will rain is 0.85 or 85%.