If a farmer sells 15 of his goats, his stock of feed will last for 4 more days than planned, but if he buys 20 more goats, he will run out of feed 3 days earlier than planned. If no goats are sold or bought, the farmer will be exactly on schedule. How many goats does the farmer have?  Select:
A) 12
B) 24
C) 48
D) 60
E) 55
Say farmer has n goat and he is good for d days.:-   We have 3 equations given in question:-   (n-15) * d+4 =(n+20) *(d-3) = n * d   Solving these: (You can solve 1st and 3rd and 2nd and 3rd together)   We get:   20d-3n=60   4n-15d =60   =&gt; n=60   Ans 60 it is!
<result>D</result>
If a farmer sells 15 of his goats, his stock of feed will last for 4 more days than planned, but if he buys 20 more goats, he will run out of feed 3 days earlier than planned. If no goats are sold or bought, the farmer will be exactly on schedule. How many goats does the farmer have?