Question

in a group of dogs and crows number of legs is more than 2 times the number of heads by 20.what is the number of dogs ​

Answer 1

Let there be x cows and y hens. A cow has 4 legs and a hen has 2 legs.

⇒4x+2y=2(x+y)+14

⇒x=7

Answer 2

The number of dogs is 7.

Let the number of dogs = x

⇒ Total number of legs of dogs = 4x

⇒ Total number of heads of dogs = x

Let the number of crows = y

⇒ Total number of legs of crows = 2y

⇒ Total number of heads of crows = y

∴ Total number of heads = x + y

   Total number of legs = 4x + 4y

Given that the number of legs are more than twice the number of heads.

⇒ 4x + 2y = 14 + 2 (x + y)

⇒ 4x + 2y = 14 + 2x + 2y

⇒       4x   =  14 + 2x

⇒         2x = 14

⇒           x = 7

Thus the number of dogs = x = 7.

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