Answer
$ŷ =0.000017x+119.2$
(Results from Minitab; other methods can give slightly different results.)
Work Step by Step
In MINITAB, enter the MRI count values in C1 and in C2 enter the IQ values.
Select Stats -> Regression -> Regression -> Fit Regression Model
Enter C2 in "Responses" and C1 in "Continuous Predictors"
The least-squares regression line ($ŷ =b_1x+b_0$) will be shown in "Regression Equation", where C2 is $ŷ $ (IQ) and C1 is $x$ (MRI count).
