Question

cost of 10 pens and 5 eraser is rupees 11.25 .cost of 10 erasers and 5 pens is 7.5 then find the cost of one pen and one eraser together​

Answer 1

Step-by-step explanation:

let cost of one pen be x

and cost of one eraser be y

cost of 10 pens and 5 erasers is 11.25

10x + 5y = 11.25...............(1)

cost of 5 pens and 10 erasers is 7.5

5x + 10y = 7.5.............(2)

multiply 2 for (2)

then

10x + 20y = 15........(3)

now solve (1) and (3)

10x + 20y = 15

10x + 5y = 11.25

15y = 3.75

y = 0.25

substitute in (1)

10x + 5(0.25) = 11.25

10x + 1.25 = 11.25

10x = 11.25-1.25

10x = 10

x = 1

therefore, cost of one pen is 1rs

and cost of one eraser is 0.25 rs

Answer 2

Answer:

Step-by-step explanation:

Let the cost of 1 pen=x

And of 1 eraser=y

So10x+5y=11.25 (1)

Then 5x+10y=7.5 (2)

10x+5y=11.25

5x+10y=7.5

Then. We will multiply 5with 10x and 10 with 5x to make them equal

10x×5+5y×5=11.25×5

5x×10+10y×10=7.5×10

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