Question

Two charged bodies of charge + 3.0uc and + 7uc and brought in contact for a while and separated.
What are the charges on the bodies now?

Answer 1

The law of conservation of a charge says

$$q_1+q_2=q_1'+q_2'=2q'$$

Hence

$$q'=\frac{q_1+q_2}{2}=\rm\frac{3.0\:\mu C+7.0\:\mu C}{2}=5.0\:\mu C$$