In a farm, there are cows and hens. If heads are counted there are 180, if legs are counted there are 420. The number of cows in the farm is [WBSSC 2015] |
A) 150
B) 30
C) 130
D) 50
Correct Answer: B
Solution :
Let the number of cows and hens in the farm be x and y, respectively. |
Then, \[x+y=180\] (i) |
and \[4x+2y=420\] |
\[\Rightarrow \] \[2x+y=210\] (ii) |
On subtracting Eq. (i) from Eq. (ii), we get |
\[x=30\] |
Hence, there are 30 cows in the farm. |
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