A downward sloping straight line shows what relationship?

A line is represented mathematically by a "linear"
equation, which takes the following standard form:

y = mx +
b

This equation defines the point y given the input x, and
parameters m and b.

m is the slope. A downward sloping
straight line will have a negative value of m. What this means is that as x increases in
value, y decreases in value. Thus there is a negative correlation between the variables
x and y. The parameter b establishes a fixed reference point, namely the point
(0,b).