A man has some hens and cows. If the number of heads be 50 and the number of feet equals 140, then the number of hens will be:
Choose the most appropriate option
A) 22
B) 23
C) 24
D) 30
E) 28

Rationale: "let hens be x and cows be y now , feet : x * 2 + y * 4 = 140 heads : x * 1 + y * 1 = 50 implies , 2 x + 4 y = 140 and x + y = 50 solving these two equations , we get x = 30 and y = 20 therefore , hens are 26 . answer : d"
Answer: D