A horse uses 250n to pull a cart through 10m of mud. Here is how to calculate how
much work the horse has done.

Hey,
If we assume that the horse is pulling a cart on a horizontal support AB (of mud).
Then,
[tex]\sum\overrightarrow{F_{AB}}= ||\overrightarrow{F}|| \times AB = 250 \times 10= 2,50 \times 10^3 J[/tex]
But maybe it's reasonable to download the image, if you can.