Uncle Ben has four horses. Each horse can consume five pounds of oats per meal. He feeds his horses twice a day. If one bag contains 50-pounds of oats,  how many bags of oats does he need to fed his horses for five days?
The four horses can consume 4 x 5 pounds = 
<gadget id="calculator">4*5</gadget>
<output>20</output>
20 pounds of oats per meal.
Thus, they can consume 2 x 20 pounds = 
<gadget id="calculator">2*20</gadget>
<output>40</output>
40 pounds of oats a day.
So, uncle Ben needs 5 x 40 pounds = 
<gadget id="calculator">5*40</gadget>
<output>200</output>
200 pounds of oats to fed his horses for five days.
Therefore, uncle Ben needs 200/50 = 
<gadget id="calculator">200/50</gadget>
<output>4</output>
4 bags of oats.

<result>4</result>