Explain how the fountain pen is filled up with ink​

A piston-filling fountain pen has a piston — just like in a car — inside the barrel. This piston goes down to expel air or ink and then back up, pulling ink into the barrel. The typical process is very simple, assuming the pen is clean and dry: Push the piston down, expelling any air in the barrel

c. newton's third law of motion

305.7

explanation:

density =m/v

density =917/3.00

density = 305.

approximately = 305.7

in four significant figures