In reply to VK.

Sure. Just substitute the value of the WEIGHT variable into the model. For this example, the model is approximately
Y = 60.4 -0.12*Horsepower -0.01*Weight + 0.000028*Horsepower*Weight
So if you plug in, say, Weight=1850, you get the equation of the model at that fixed value of Weight.
The model becomes
Y = 41.9 - 0.0682*Horsepower.