Maybe if multiply 80 by 3 so you can find one of the answer then do it algebraic
Let us assume that even F represents fidelity and event S represents selectivity.
We have been given the probabilities:
P(S) = 0.72, P(F) = 0.59 and 
We need to find the conditional probability that a system with high fidelity will also have high selectivity. We know the conditional probability formula:

Upon substituting the given values, we get:


Answer: 3
Step-by-step explanation:
Let's create a model first.
The initial fee is $19 (this is our y intercept or b)
And the pay per is $4 (this is our variable or m)
y=mx+b
y= 4x+19
To find out what the maximum number of events someone can attend for $31, we plug in different number for the x value until it's less than or equal to $31
In this case, plugging in 3 for x gives us exactly $31
y=4(3)+19= 31