Question

find the slope of the line that passes through the pair of points (4.5, 13.5) and (–3.5, –9).

Answer 1

Given two points: (x₁,y₁) and (x₂,y₂) the slope "m" will be:
m=(y₁-y₂) / (x₁-x₂)                or                  m=(y₂-y₁) / (x₂-x₁)

In this case:
(4.5 , 13.5)
(-3.5 , -9)

m=(-9-13.5) / (-3.5-4.5)=-22.5 / -8=2.8125

Answer: the slope will be m=2.8125.