In a farm, there are cows and hens. The total number of heads is 50 and the total number of legs is 140. How many cows are there?
Show answer & explanation
Correct answer: A
Explanation
Let:
Number of cows = x
Number of chickens = y
Number of heads:
x + y = 50
Number of legs:
4 legs of a cow → 4x
2 legs of a chicken → 2y
4x + 2y = 140
From the first equation:
y = 50 − x
Substituting into the second:
4x + 2(50 − x) = 140
4x + 100 − 2x = 140
2x = 40
x = 20
Therefore, the number of cows = 20