Problem: if a farmer sells 15 of his chickens , his stock of feed will last for 4 more days than planned , but if he buys 25 more chickens , he will run out of feed 3 days earlier than planned . if no chickens are sold or bought , the farmer will be exactly on schedule . how many chickens does the farmer have ?
Rationale: "say farmer has n chicken and he is good for d days . : - we have 3 equations given in question : - ( n - 15 ) * d + 4 = ( n + 25 ) * ( d - 3 ) = n * d solving these : ( you can solve 1 st and 3 rd and 2 nd and 3 rd together ) we get : 25 d - 3 n = 75 4 n - 15 d = 60 = > n ~ 49 ans e it is !"
annotated_formula: multiply(add(const_2, 4), multiply(3, 4))