Answer
$ŷ=-12.509+1.3341x_1-0.4143x_2$
Work Step by Step
In MINITAB, enter the air temperature values in C1, the wind speed values in C2 and the wind chill values in C3.
Select Stats -> Regression -> Regression -> Fit Regression Model
Enter C3 in "Responses" and C1 C2 in "Continuous Predictors"
The least-squares regression line will be shown in "Regression Equation", where C3 is $ŷ$ (wind chill), C1 is $x_1$ (air temperature) and C2 is $x_2$ (wind speed).
$ŷ=-12.509+1.3341x_1-0.4143x_2$
