Rhia is using the above equation to investigate the carbon footprint, ccc, in kilograms of carbon dioxide (co_2)(co 2 ​ )left parenthesis, c, o, start subscript, 2, end subscript, right parenthesis emissions, for her morning commute, during which sss miles are by subway and bbb miles are by bus. how many kilograms of co_2co 2 ​ c, o, start subscript, 2, end subscript per mile does the bus portion contribute to rhia's carbon footprint?