Linear Equations in One Variable

SAT Math· difficulty 4/5

A farm has chickens and cows. Total heads = 50, total legs = 140. How many cows?

  • A

    25

  • B

    30

  • C

    20

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  • D

    15

Explanation

c+k=50c + k = 50, 4c+2k=1404c + 2k = 140. Sub: 4c+2(50c)=1404c + 2(50-c) = 1402c=402c = 40c=20c = 20 cows.

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