Let x, y and z denote the weighs of car X, car Y and car Z, respectively.
We know that car X weighs 136 more than car Z, this can be express by the equation:
We also know that Y weighs 117 pounds more than car Z, this can be express as:
Finally, we know that the total weight of all the cars is 9439, then we have:
Hence, we have the system of the equations:
To solve the system we can plug the values of x and y, given in the first two equations, in the last equation; then we have:
Now that we have the value of z we plug it in the first two equations to find x and y:
Therefore, car X weighs 3198 pound, car Y weighs 3179 pounds and car Z weighs 3062 pounds.