The chlorine isotope with 18 neutrons has an abundance of 0.7577 and a mass number of 35 amu. To calculate the average atomic mass, multiply the fraction by the mass number for each isotope, then add them together.
Equal is the answer
Hope this helps
Walking is what i think you are talking about
Volume can be measured in cubic centimetres (which is the small 3 next to the unit and is higher)
Matter is anything that occupies space and has mass.