In a petting zoo, there are 50 hens, there are 40 goats, and 10 llamas with some humans. If the total number of feet are 210 more than the number of heads in the zoo, the number of humans is  Choices.
A) 1
B) 5
C) 10
D) 15
E) 20
Explanation: Let number of humans be x. Then, Total number of feet = 2 x 50 + 4 x 40 + 4 x 10 + 2x = 2x + 300 Total number of heads = 50 + 40 + 10 + x= 100 + x. Therefore (2x + 300) = (100 + x) + 210 or x = 10. Answer: 10
<result>C</result>
In a petting zoo, there are 50 hens, there are 40 goats, and 10 llamas with some humans. If the total number of feet are 210 more than the number of heads in the zoo, the number of humans is