The country of China has 9.6 million km^2 of area. Suppose the government embarks on a comprehensive sequestration program in which 5% of this area is targeted for reforestation with a species of tree that can absorb 1.4 kg carbon/m2 ·year net for 20 years, after accounting for carbon emissions associated with the executing the project, for example, transporting tree seedlings, equipment for planting, and so on. In order to develop the reforested area evenly, the project is divided into two phases. In the first phase, the reforestation project starts from a small scale in the year 2010 and follows a triangle curve in reaching 100% of annual capacity to plant trees over 10 years. In the second phase, planting continues at a constant rate of 50,000 km^2 /year until all the area has been reforested. Over the life of the project, emissions from the Chinese economy are projected to start at 7 Gt/year in 2010 and grow linearly by 0.27 Gt/year. a. How many years does it take to plant the entire area with trees, to the nearest whole year?

b. Over the lifetime of the project, what is the percentage of total of carbon emissions from the economy sequestered by the project?