The bird watcher saw 7 blue Jays?
You will substrate the percentage of the sale price with the regular price

Substitute the values of x to the equation of the function f:

Therefore we have two points (-1, 7) and (2, 1).
We can calculate the slope of line l.
The formula of a slope:

Substitute:

<h3>Answer: A) -2.</h3>
Answer: If the number of bills counted is odd, the ones digit is 5; if the number of bills is even, the ones digit is 0.
Explanation
1) Simulate the counting of the bills:
number of bills counted value ones digit
1 5 5
2 5 + 5 = 10 0
3 10 + 5 = 15 5
4 15 + 5 = 20 0
5 20 + 5 = 25 5
6 25 + 5 = 30 0
2) Pattern: you can see that the ones digit alreternate: 5, 0, 5, 0, 5, 0, ...
If the number of bills counted is odd the ones digit is 5, if the number of bills is even the ones digit is 0.