The coefficients in a chemical equation represent the molar ratio of the substances.
For example, if an equation says 2H2 + O2 ⇒ 2H2O, it means
2 moles of H2 + 1 mol of O2 ⇒ 2 moles of H2O.
2 cm east is the answer because you go east 5.5 cm and then go back in a sense 3.5 so its basically 5.5-3.5 because its backwards while still facing eat
Precision is obtained by getting values that are very close together. If you mess around with the protocol, you'll end up with crazy values that probably are neither accurate or precise.
In order of relative atomic mass.