Let's play in the park

Algebra Level 1

In a children's park, the ratio of the number of adults to the number of children is $1:4$ . After five minutes, $1$ adult and $10$ children came. The ratio became $1:5$ . What was the original number of adults?

The answer is 5.

1 solution

A Former Brilliant Member
Apr 12, 2018

Let $A$ be the original number of adults and $C$ be the original number of children. Then we have the two equations:

$\dfrac{A}{C}=\dfrac{1}{4}$ and $\dfrac{A+1}{C+10}=\dfrac{1}{5}$

Solving the system of equations gives $A=5$ and $C=20$ . The desired answer is $\boxed{5}$

Let's play in the park

The answer is 5.

1 solution

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