Question

Meena and Teena went to book shop and bought some exercise notebooks. They had Rs
100 each. Meena could buy 7 large and 4 small notebooks. Teena could buy 5 large and 6 small
notebooks and had Rs 5 left. What is the cost of large notebook?

Answer 1

Answer:

let cost of large note book is Rs x

and cost of small note book is Rs y

then,

7x+4y=100

4y=100-7x

=> y= (100-7x)/4

5x+6y=(100-5)

5x+6.(100-7x)/4=95

=> 5x+3(100-7x)/2=95

=> 10x+300-21x=95×2

=> -11x=190-300

=> -11x= -110

=> x= -110/ -11

=> x=10

so, cost of large note book is Rs 10

Answer 2

Question :-

Meena and Teena went to book shop and bought some exercise notebooks. They had Rs 100 each. Meena could buy 7 large and 4 small notebooks. Teena could buy 5 large and 6 small notebooks and had Rs 5 left. What is the cost of large notebook?

$\large\underline{\sf{Solution-}}$

Given that,

Meena and Teena went to book shop and bought some exercise notebooks. They had Rs 100 each. Meena could buy 7 large and 4 small notebooks. Teena could buy 5 large and 6 small notebooks and had Rs 5 left.

Let assume that

Cost of 1 large notebook be Rs x

Cost of 1 small notebook be Rs y.

According to first condition,

Meena purchade 7 large and 4 small notebooks for Rs 100.

Cost of 1 large notebook = Rs x

So, Cost of 7 large notebooks = Rs 7x

Also, Cost of 1 small notebook = Rs y

So, Cost of 4 small notebooks = Rs 4y

Thus,

$\rm\implies \:7x + 4y = 100 \: \: - - - - (1)$

According to second condition,

Teena purchade 5 large and 6 small notebooks for Rs 95.

Cost of 1 large notebook = Rs x

So, Cost of 5 large notebooks = Rs 5x

Also, Cost of 1 small notebook = Rs y

So, Cost of 6 small notebooks = Rs 6y

Thus,

$\rm\implies \:5x + 6y = 95 \: \: - - - - (2)$

Now, we solve these two equations using elimination method.

So, multiply equation (1) by 3 and equation (2) by 2, we get

$\rm\implies \:21x + 12y = 300 \: \: - - - - (3)$

and

$\rm\implies \:10x + 12y = 190 \: \: - - - - (4)$

Now, On Subtracting equation (4) from equation (3), we get

$\rm \: \: 11x= \: 110$

$\rm\implies \:x = 10$

So, it means Cost of 1 large notebook = Rs 10