First, we need to find the area of the sidewalk that he will be shoveling:
[tex]A=l*w[/tex]
In this case, l=2m and w=40m. Then we have
[tex]A=2*40=80m^{2}[/tex]
We know that he can shovel [tex]20m^{2}[/tex] in 10 minutes, so this would take him 40 minutes since 20*4=80. Now we just need to figure out how much this will cost. Since he charges $5.00 per half hour, we need to get 40 minutes in terms of half hours:
[tex]\frac{40}{30}=\frac{4}{3}[/tex]
Last, we just multiply his half-hour rate by the amount of half hours he is shoveling for:
[tex]\frac{4}{3}(5)=\frac{20}{3}[/tex]
I'll let you simplify the fraction.
