A man has some hens and cows. If the number of heads be 48 and the number of feet equals 140, then the number of hens will be:

Let the number of hens be x and the number of cows be y.

Then, x + y = 48 .... (i)

  and 2x + 4y = 140      x + 2y = 70 .... (ii)

Solving (i) and (ii) we get: x = 26, y = 22.

 The required answer = 26.