Question

The ratio of number of cats to the number of dogs owned by the children in a particular age group in a school is $5:4$ . There are $60$ dogs . How many cats do they have ?

Answer 1

Given: ratio of age of cats and dog $=5:4$

No of dogs $=60$

Let: No of cats be $=x$

It is written as $cats:dog=5:4$

$x:60:\hspace{0.17em}:5\hspace{0.17em}:4$

First and last term is called extreme terms, that is $x$ and $4$ and $60$ and $5$ is called middle terms.

product of extreme terms = product of middle terms

$$\begin{gathered} x\times 4=60\times 5 \\ x=\frac{60\times 5}{4} \\ x=\frac{{\displaystyle \stackrel{15}{\cancel{60}}\times 5}}{{\displaystyle \underset{1}{\cancel{4}}}} \\ x=15\times 5 \\ \therefore x=75 \end{gathered}$$

Hence the number of cats are $75.$