Question

15 pens and 3 notebooks cost Rs. 300. 4 pens and 2 notebooks cost Rs. 110. How much is cost of notebook and pen respectively?​

Answer 1

Answer:

Solution:

3 Pen +4 Notebook =110 rupees

Multiply by 5,

15 Pen +20 Notebook =550 rupees

7 Pen +5 Notebooks =170 rupees

Multiply by 4,

28 Pen +20 Notebook =680 rupees

15 Pen +20 Notebook =550 rupees

Equating and solving for Pen,

Cancelling notebook,

13 Pen =130 Hence,

Pen =10 rupees

Substituting,

3(10)+4 Notebook =110

4 Notebook =110−30 Hence,

Notebook =20 rupees

Step-by-step explanation:

Answer 2

The cost of pen is Rs. 15 and cost of notebook is Rs. 25.

Given - Relation

Find - Cost of notebook and pen

Solution - Let the number of pens be x and notebooks be y. So, equation 1 will be -

15x + 3y = 300

And equation 2 will be -

4x + 2y = 110

Multiplying equation 1 with 2 and equation 2 with 3. So, we get new equations as -

30x + 6y = 600 - Equation 3

12x + 6y = 330 - Equation 4

Subtracting equation 4 from equation 3. We get -

30x - 12x = 600 - 330

18x = 270

x = 270/18

x = 15

Keep the value of x in equation 2 to find the cost of notebook.

4*15 + 2y = 110

2y = 110 - 60

2y = 50

y = 50/2

y = 25

Hence, cost of pen is Rs. 15 and cost of notebook is Rs. 25.

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