Answer:
2.0
Step-by-step explanation:
x = age
y = average systolic blood pressure
x₁ = 40 years old, y₁ = 110 systolic blood pressure
x₂ = 50 years old, y₂ = 130 systolic blood pressure
[tex]\text{Slope of a line}=m=\frac{y_2-y_1}{x_2-x_1}\\\Rightarrow m= \frac{130-110}{50-40}\\\Rightarrow\frac{20}{10}\\\Rightarrow m= 2.0[/tex]
∴ Slope of the regression line is 2.0