Question

Dan is watching the birds in his backyard.

Of the birds he watches, $9$ of them, or $45\%$, are sparrows.

How many birds are in his backyard?

Answer 1

Finding the total number of birds:

Let us suppose total number of birds in the backyard of Dan is $x$

It is given that out of total birds $45\%$, are sparrows and in numbers it's $9$ which means $45\%$ of $x$ is $9$ so, we get

$$\begin{gathered} \left(x\right)\times \frac{45}{100}=9 \\ \Rightarrow x=\frac{900}{45} \\ \Rightarrow x=20 \end{gathered}$$

Hence, the total number of birds in the backyard of Dan is $20$.