In the table, x represents the age in years of a collectible baseball card, and y represents its value in dollars.

Cost of a Pack of Baseball Cards
Age in years, x
Value in dollars, y
5
0.75
10
5.75
15
10.75
20
15.75

Which statement is correct about the slope of the linear function that the table represents?
The slope is positive because as the age decreases, the value increases.
The slope is positive because as the age increases, the value increases.
The slope is negative because as the age decreases, the value decreases.
The slope is negative because as the age increases, the value decreases.