What is the net charge of an ion that has 8 protons, 9 neutrons, and 10 electrons

The answer is -2, but why?

The protons are positively charged, and have a value of +1 each. The electrons are negatively charged and have a value of -1 each. The neutrons have no charge, and have a value of 0. So, add them all up. (+8)+ (0) +(-10) = -2

Remember:
Protons = Charge of +1...you have 8 of these of +8
Neutrons = Charge of 0...You have 9 of these but they don't have any charge so +0
Electrons = Charge of -1...You have 10 of these so -10
So +8(protons) +0(neutrons) -10(electrons) = -2

Electrons have a negative charge, and there are two more electrons than protons. The others cancel each other out, but the extra electrons create a net charge of -2.