Answer:
The wife have to sit at 0.46 L from the middle point of the seesaw.
Explanation:
We need to make a sketch of the seesaw and the loads acting over it.
And by the studying of the Newton's law we can find the equation useful to find the distance of the mother sitting on the seesaw with respect to the center ot the pivot point.
A logical intuition will give us the idea that the mother will be on the side of her son to make the balance.
The maximum momentum with respect to the pivot point (0) will be:

Where L/2 is the half of the distance of the seesaw
Therefore the other loads ( mom + son) must be create a momentum equal to the maximum momentum.
It would be tt because the lower case has to be in the beginning in order to be recessive
Density of Earth: 5.514 g/cm³
Density of Jupiter: <span>1.326 g/cm³
1.326 g/cm³ / 5.514 g/cm³ </span>≈ <span>0,24
0,24 * 100 = 24%
Jupiter has 24% of earth's density.
(Density numbers are from internet, you may calculate with your own ones if u have )</span>
I don't know how to anwser this but and gas hybrid uses and gas powered motor so tiny explosions inside of the cyiliders but the electric car uses and electric motor powered by a simple battery...I still don't know if this is correct....