A large electric utility company spews million tons of greenhouse gases (mostly carbon dioxide) into the environment each year. This company has committed to spending $ billion in capital over the next five years to reduce its annual emissions by %. More will be spent after five years to reduce greenhouse gases further. a. What is the implicit cost of a ton of greenhouse gas? b. If the United States produces billion tons of greenhouse gases each year, how much capital must be spent to reduce total emissions by % over the next five years based on your answer in Part (a)?