If a farmer sells 15 of his hens, his stock of feed will last for 4 more days than planned, but if he buys 20 more hens, he will run out of feed 3 days earlier than planned. If no hens are sold or bought, the farmer will be exactly on schedule. How many hens does the farmer have? Choices:
A) 60	B) 40	C) 80	D) 70	E) 50
Let x = total feed required for the planned period   n= number of hen   t = total time of the planned feed   x = nt   1) x = (n-15) * (t+4)   2) x = (n+20) * (t-3)   equating 1&amp;2   (n-15) * (t+4) = (n+20) * (t-3) or nt +4n -15t -60 = nt -3n +20t-60   7n = 35t   n =5t   x= n * n/5   substituting this value in 1   n * n/5 = (n-15) * (n/5+4)   5n = 300   n =60   60
<result>A</result>
If a farmer sells 15 of his hens, his stock of feed will last for 4 more days than planned, but if he buys 20 more hens, he will run out of feed 3 days earlier than planned. If no hens are sold or bought, the farmer will be exactly on schedule. How many hens does the farmer have?