There are 336 girls at a concert. The ratio of girls to boys at the concert is 4 to 5. How many total girls and boys are at the concert.

Given that there are $336$ girls at a concert and the ratio of girls to boys at the concert is $4 to 5$.

We have to find the total number of girls and boys are at the concert.

Since, the ratio of girls to boys at the concert is $4 to 5$

Let the total number of girl is $4x$ and total number of boys is $5x$.

Sine, given there are $336$ girls at a concert

$\begin{array}{l}\Rightarrow 4x=336\\ \Rightarrow x=\frac{336}{4}\\ \Rightarrow x=84\end{array}$

Hence, $x=84$

So, total number of boys is $5\times 84=420$