The area of a trapezoid is given by:
[tex]A=\frac{a+b}{2}h[/tex]
where a and b are the bases and h is the height.
Plugging the values given we have that the area is:
[tex]\begin{gathered} A=\frac{70+130}{2}\cdot50 \\ A=\frac{200}{2}\cdot50 \\ A=100\cdot50 \\ A=5000 \end{gathered}[/tex]
Hence the area of the trapezoid is 5000 squared ft.
Now, to determine the number of bags must be purchased we divide the total area by the amount each bag covers:
[tex]\frac{5000}{2400}=2.08[/tex]
Threfore we have to buy three bags of fertilizer to cover the lawn. (We have to round up in this case since we can't buy a decimal amount of a bag, that's why we have to buy three and not two)
