Question

20 pens cost 140 rupees, what is the cost of 12 such pens? *
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Answer 1

Answer:

cost of 20pens =140

cost of 1 pen=140/20

=₹7

Cost of 12 such pens=₹7×12

=₹84

Answer 2

Given :

• Cost of 20 pens = Rs. 140

To Find :

• Cost of 12 pens = ?

Solution :

We are given :

Cost of 20 pens = Rs. 140

Now,

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

By substituting the values :

$\sf : \implies Cost \: of \: 1 \: pen = \dfrac{Rs. \: 140}{20}$

$\sf : \implies Cost \: of \: 1 \: pen = \dfrac{Rs. \: \cancel{140}}{\cancel{20}}$

$\sf : \implies Cost \: of \: 1 \: pen = Rs. \: 7$

Now, we have to find cost of 12 pens :

Cost of 12 pens = cost of 1 pen × 12

By filling values :

$\sf : \implies Cost \: of \: 12 \: pen = Rs. \: 7 \times 12$

$\sf : \implies Cost \: of \: 12 \: pen = Rs. \: 84$

Hence, cost of 12 pens is Rs. 84.