He feeds each horse 2*20=<<2*20=40>>40 pounds of food a day
So he uses 40*25=<<40*25=1000>>1000 pounds of food a day
That means in 60 days he uses 60*1000=<<60*1000=60000>>60000 pounds of food
Each bag of food is 2000*.5=<<2000*.5=1000>>1000 pounds
So he needs to buy 60000/1000=<<60000/1000=60>>60 bags of food
#### 60