Question

Deepak bought 3 notebooks and 2 pens for Rs 80. His friend Ram said that price of each notebook could Rs 25. Then three notebooks would cost Rs 75. The two pens would cost Rs 5 and each pen could be for Rs. 2.50. Another friend Ajay felt that Rs 2.50 for one pen was too little. It should be at least Rs 16. Then the price of each notebook would also Rs 16. Lohith also bought the same types of notebooks and pens as Aditya. He paid 110 for 4 notebooks and 3 pens. Later, Deepak guess the cost of one pen is Rs 10 and Lohith guess the cost of one notebook is Rs 30. (1) Form the pair of linear equations in two variables from this situation by taking cost of one notebook as Rs x and cost of one pen as Rs y.​

Answer 1

Answer:

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Answer 2

Answer:

hope it helps

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Step-by-step explanation:

Here it is given that cost of one notebook be x and that of pen be y .

Then cost of 3 notebooks and 2 pens

= \sf{3x + 2y}=3x+2y

Again cost of 4 notebooks and 3 pens

\sf{ = 4x + 3y}=4x+3y

So by the given condition

\sf{3x + 2y = 80 \: \: \: ....(1)}3x+2y=80....(1)

\sf{4x + 3y = 110 \: \: \: ...(2)}4x+3y=110....(2)

Which is set of equations to describe the given problem

Hence the set describe the given problem is

(b) 3x + 2 y = 80 and 4x + 3 y = 110

Now we solve from x and y

Multiplying Equation (1) by 3 and equation (2) by 2 we get

\sf{9x + 6y = 240}9x+6y=240

\sf{8x + 6y = 220}8x+6y=220

On substraction we get x = 20

From Equation (1) we get y = 10

Hence cost of one notebook is 20 and that of pen be 10

Ramesh said that price of each notebook could be Rs. 25

So Ramesh's estimation is wrong

Amar felt that Rs. 2.50 for one pen was too little. It should be at least Rs. 16

So Amar's estimation is wrong

( II ) Whether the estimation of Ramesh and Amar is applicable for Lokesh

(d) Ramesh’s estimation is wrong but Amar’s estimation is also wrong.

Solving Equation (1) & Equation (2)

we get x = 20 & y = 10

( III ) The exact cost of the notebook

(b) Rs 20

( IV ) The exact cost of the pen

(a) Rs 10

The cost of 15 notebooks

= Rs ( 15 × 20 )

= Rs 300

The cost of 12 pens

= Rs ( 12 × 10 )

= Rs 120

Hence total cost

= Rs ( 300 + 120 )

= Rs 420

The total cost if they will purchase the same type of 15 notebooks and 12 pens.

(c) Rs 420