Answer:
[tex]27,648,000[/tex]
Step-by-step explanation:
The area of a rectangle is given by [tex]l\cdot w[/tex]. Landen's 20 feet by 80 feet front lawn therefore has an area of [tex]20\cdot 80 = \fbox{$1600\: \mathrm{ft^2}$}[/tex].
He counts there are 120 blades of grass per square inch. There are [tex]12^2=144[/tex] square inches in one square foot.
Therefore, his lawn has an area of [tex]1600\: \mathrm{ft^2}\cdot \frac{144\:\mathrm{in^2}}{1\:\mathrm{ft^2}}=230,400\:\mathrm{in^2}[/tex].
Thus, there are [tex]230,400\:\mathrm{in^2}\cdot 120=\fbox{$27,648,000$}[/tex] blades of grass in the entire lawn.
