The graph below shows how the rate of carbon dioxide emissions varies from 1800 to 2020.

By using the appropriate lines of best fit from the graph,
a) Work out an estimate for the amount of carbon dioxide emitted between the years 1870 and 1930. Give your answer in kg, in standard form to 3 significant figures.
[4 marks]
b) Work out an estimate for the amount of carbon dioxide emitted between the years 1960 and 1990. Give your answer in kg, in standard form to 3 significant figures.
[4 marks]
c) Compare the amount of carbon dioxide released in the 60 years between 1870 and 1930 and in the 30 years between 1960 and 1990.
[2 marks]