Question

If the cost of 12 pens is rs 18, find the cost of 30 pens​

Answer 1

Answer:

Given :

Cost of 12 pens = Rs. 18

To Find :

Cost of 30 pens = ?

Solution :

We are given :

Cost of 12 pens = Rs. 18

Now,

\sf Cost \: of \: 1 \: pen = \dfrac{Total \: cost \: of \: pens}{Total \: no. \: of \: pens}Costof1pen=

Totalno.ofpens

Totalcostofpens

By substituting the values :

\sf : \implies Cost \: of \: 1 \: pen = \dfrac{Rs. \: 18}{12}:⟹Costof1pen=

12

Rs.18

\sf : \implies Cost \: of \: 1 \: pen = Rs. \: 1.5:⟹Costof1pen=Rs.1.5

Now, we have to find cost of 20 pens :

Cost of of 30 pens = cost of 1 pen × 30

By filling values :

\sf : \implies Cost \: of \: 30 \: pen = Rs. \: 1.5\times 30:⟹Costof30pen=Rs.1.5×30

\sf : \implies Cost \: of \: 30 \: pen = Rs. \: 45:⟹Costof30pen=Rs.45

Hence, cost of 30 pens is Rs. 45

Answer 2

Given data,

The cost of $12$ pens is $18$ rupees

We have to find out the cost of $30$ pens.

In order to find out the cost of $30$ pens,

First we have to find the cost of one pen.

The cost of one pen is calculated as,

Cost of  $12$ pens is divided with $18$ rupees

$\frac{18}{12}$

$1.5$

The cost of one pen is $1.5$

The cost of one pen is multiplied with $30$ pens to get cost of  $30$  pens.

$30\times1.5$

$45$

Therefore, the cost of  $30$ pens is $45$