If a farmer sells 5 of his chickens, his stock of feed will last for 4 more days than planned, but if he buys 20 more chickens, he will run out of feed 1 day earlier than planned. If no chickens are sold or bought, the farmer will be exactly on schedule. How many chickens does the farmer have? Pick one:
A) 15
B) 20
C) 20/3
D) 25
E) 10
Let x = total feed required for the planned period   n= number of chicken   t = total time of the planned feed   x = nt   1) x = (n-5) * (t+4)   2) x = (n+20) * (t-1)   equating 1 &amp;2   (n-5) * (t+4) = (n+20) * (t-1)   5n = 25t   n =5t   x= n * n/5   substituting this value in 1   n * n/5 = (n-5) * (n/5+4)   15n = 100   n =20/3   20/3
<result>C</result>
If a farmer sells 5 of his chickens, his stock of feed will last for 4 more days than planned, but if he buys 20 more chickens, he will run out of feed 1 day earlier than planned. If no chickens are sold or bought, the farmer will be exactly on schedule. How many chickens does the farmer have?