[tex]a\ single\ tree \ \ \ \rightarrow\ \ \ about\ 2.6 \cdot10^2\ lb\ of\ oxygen\ each\ year\\\\the\ rainforest\ \ \ \rightarrow\ \ \ about\ 3.9 \cdot 10^{11}\cdot2.6 \cdot10^2\ lb\ each\ year\\\\3.9 \cdot 10^{11}\cdot2.6 \cdot10^2=10.14\cdot10^{13}\\\\\\10.14\cdot10^{13}\ \ \ \rightarrow\ \ \ each\ year\\\\ \frac{\big{10.14\cdot10^{13}}}{\big{365}} \approx0.028\cdot10^{13}=2.8\cdot10^{11}\ \ \ \rightarrow\ \ \ dailly\\\\Ans.\ About\ 2.8\cdot 10^{11}\ lb\ each\ day.[/tex]
