Planet$-$wide, humans are adding about $40$billion metric tons of CO$2$to the atmosphere every year. The USA$$s contribution to this is about $6$billion metric tons of CO$2$per year. $$This is about half $$that of China $($although China has $4$times the population, so the US emissions per person are twice that of China$$s$)$

a$.$If we take the US population to be $333$million people, how many metric tons is the average person in the US responsible for emitting per year? $($Round off to the nearest metric ton.$)$

$\_\_\_\_\_\_\_$metric tons

b$.$An average wind turbine $(1\mathrm{.}82$MW$)$offsets $3700$metric tons of carbon dioxide every year. There are approximately $70,000$wind turbines in the USA currently. How many wind turbines would be needed to offset $100\%$of the US emissions? $($We$\text{'}$re looking for the total number, including what already exists.$)$

$\_\_\_\_\_\_\_$wind turbines