Answer
$C_6H_{12}O_6 +6O2 <=> 6CO_2 + 6H_2O +ENERGY$
This is the equation of cellular respiration. We take the sugars from our food (or in plants from photosynthesis) and oxygen that we breathe in and create three products. $CO_2$ we breath out, $H_2O$ we breath out and absorb and we have energy in the form of ATP. ATP is used for all cellular processes.
Work Step by Step
This is related to breathing because we breathe in oxygen which is used to create ATP. Then once the process is done, we breathe out the $CO_2$.