How does a positively charged metal ball become neutral

By gaining equal number of electrons to the charge it carries.

Explanation:

A positively charge metal ball will become if it gains equal number of electrons to the charge it carries.

Generally, a body becomes charged when they lose or gain electrons. The loss or gain of electrons by a body is common place feature. Merely rubbing of substances against each other will cause a loss or gain of electrons.

Electrons are negatively charged particles in an atom

Protons are positively charged particles.

In a neutral atom, the number of protons and electrons must be the same.

A positively charge body will have more number of protons than electrons.

To make a positively charged metal become neutral, we bring it to the vicinity of electrons.

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)