If the total mass of carbon contained in fossil fuels that was burned in the world from 1750 to 2000 is estimated to be 2.77e14 kilogram carbon. The quantity of carbon released as carbon dioxide from agricultural expansion as well as deforestation over this period is estimated at 1.31e14 kilogram carbon. State the concentration of CO2 in the atmosphere in 2000 was 393ppm corresponding to a total mass of 7.75e14 kilogram carbon. Compute the percentage of CO2 from these two sources that remain in the atmosphere over the 2.5 century period