Pets in ZOO

The zoo has run for pets. They are chickens, pigs, and cows. Altogether there has 20 heads and 60 feet. How many chickens and piglets are there?

Correct answer:

x =  10
y =  9

Step-by-step explanation:


x+y+1 = 20
2x+4y+4=60

x+y+1 = 20
2·x+4·y+4=60

x+y = 19
2x+4y = 56

Pivot: Row 1 ↔ Row 2
2x+4y = 56
x+y = 19

Row 2 - 1/2 · Row 1 → Row 2
2x+4y = 56
-y = -9


y = -9/-1 = 9
x = 56-4y/2 = 56-4 · 9/2 = 10

x = 10
y = 9

Our linear equations calculator calculates it.



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