Question

The price of 5 notebooks and 4 pens is 190 rupees. The price of 10 notebooks and 7 pens is 370 rupees. what is the price of a notebook. what is the price of a pen​

Answer 1

Given :-

• The price of 5 notebooks and 4 pens is 190 rupees. The price of 10 notebooks and 7 pens is 370 rupees.

To find :-

• Price of a pen and a notebook.

Solution :-

Let the price of notebook be x then price of pen be y

• According to the first condition

The price of 5 notebooks and 4 pens is 190 rupees.

→ 5x + 4y = 190 ---(i)

• According to the second condition

The price of 10 notebooks and 7 pens is 370 rupees.

→ 10x + 7y = 370 ---(ii)

Multiply (i) by 10 and (ii) by 5

• 50x + 40y = 1900
• 50x + 35y = 1850

Subtract both the equations

→ (50x + 40y) - (50x + 35y) = 1900 - 1850

→ 50x + 40y - 50x - 35y = 50

→ 5y = 50

→ y = 50/5

→ y = 10

Put the value of x in equation (i)

→ 5x + 4y = 190

→ 5x + 4 × 10 = 190

→ 5x + 40 = 190

→ 5x = 190 - 40

→ 5x = 150

→ x = 150/5

→ x = 30

Hence,

• Cost of a pen = y = Rs.10
• Cost of a notebook = x = Rs.30

Answer 2

Step-by-step explanation:

Given :-

• The price of 5 notebooks and pen is 190 rupees.

• The price of 10 notebooks and 7 pens 370 rupees.

To find :-

1. what is the price of a notebook.
2. what is the price of a pen

Solution :-

Supposed the price of notebook x and pen y

5x + 4y = 190 ..... ( 1 )

10x + 7y = 370 ..... ( 2 )

Multiply (1) by 20 and (2) by 10

100x + 80y = 3800

100x + 70y = 3700

Subtract both the equations

100x + 80y = 3800

100x + 70y = 3700

______________

10y = 100

y = 100/10

y = 10

Put the value of x in Equ ( 2 )

10x + 7y = 370

10x + 7 × 10 = 370

10x + 70 = 370

10x = 370 - 70

10x = 300

x = 300/10

x = 30

Verification :-

5x + 4y = 190

5 × 30 + 4 × 10 = 190

150 + 40 = 190

190 = 190

Hence verified

Hence, Cost of a pen Rs.10 and Cost of a notebookRs.30