a man has some hens and cows . if the number of heads be 100 and the number of feet equals 180 , then the number of hens will be :
"explanation : let the number of hens be x and the number of cows be y . then , x + y = 100 . . . . ( i ) and 2 x + 4 y = 220 x + 2 y = 110 . . . . ( ii ) solving ( i ) and ( ii ) we get : x = 90 , y = 10 . the required answer = 90 . answer : d"
divide(subtract(multiply(100, const_4), 180), const_2)