In a group of cows and hens, the number of legs are 20 more than twice the number of heads. The number of cows is :  Choose the correct choice from the following answers
A) 5  B) 6  C) 7  D) 10  E) 12
Let no of cows be x, no of hens be y.   So heads=x+y   Legs=4x+2y   Now, 4x+2y = 2(x+y)+ 20   2x = 20   x = 10.   ANSWER:10
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In a group of cows and hens, the number of legs are 20 more than twice the number of heads. The number of cows is :