What is the slope of a trend line that passes through the points (5, 80) and (7, 65)?

Given two points (x₁,y₁) and (x₂,y₂) the slope of a trend line that passes through these points would be:
m=(y₂-y₁)/(x₂-x₁)   or    m=(y₁-y₂)/(x₁-x₂);   the result would be the same.

In this case:
(5,80)
(7,65)
m=(65-80)/(7-5)=-15/2

the slope would be -15/2