Suppose we let x represent the number of dogs and y be the number of owners at the dog park. We know that a dog has four legs while a human being has two, considering that both are on normal conditions. Since both of them only have one head, we can form a system of linear equations similar to
x
+
y
=
20
4
x
+
2
y
=
62
(Eq. 1)
(Eq. 2)
We can simplify equation 2 by dividing both sides of the equation by 2. Thus, we have
2
x
+
y
=
31
(Eq. 2)
We can subtract the simplified form of equation 2 from equation 1. Subtracting allows us to eliminate the variable y. Doing so, the resulting equation is
−
x
=
−
11
Therefore, we have
x
=
11
. Using equation 1 to solve for y, we have
x
+
y
=
20
y
=
20
−
x
y
=
20
−
11
y
=
9
Therefore, there are 11 dogs and 9 humans at the dog park.