The residual is the difference between the predicted value and the real value. Using the equation, we find for the value of y using the given value of x.
y = -2.5 + 5x
y = -2.5 + 5(3)
y = 12.5
The difference between this value and the given value of y is 12.5 - 6 = 6.5
Thus, the residual is equal to 6.5.
