Electric charge

Any charge (for us..) is a multiple of an elementary charge (-e for electron, +e for proton).

Two ways to create electric charge:

1. Charging by friction. In contact, some atoms (materials) give away an electron more easily than others. Try brushing a sweater by a balloon.
2. Charging by induction. What happens if you move the balloon close to the wall?
   
   

Earthing means connection to infinite source/sink of free electrons.
There is eather attraction or repulsion between two electric cahrges. Can you state the signs of the unknown charges?