Question

Cost of 7 pens and 8 pencils is ₹ 87 and cost of 6 pens and 4 pencils is ₹66. Write the linear equation and draw the graph. Also find the cost of 1 pen and 1 pencil.

(Class9 Linear equations in two variable question )

[Note : Please don't give useless or incomplete answer ]​

Answer 1

the cost of pen is rs 9 and cost of pencil is rs 3

Answer 2

${\huge {\mathfrak {\orange {Answer :-}}}}$

Let the cost of one pencil be 'x' and the cost of one pen be 'y'.

➡️ So, 7y + 8x = 87. ...... (1)

And, we have,

➡️ 6y + 4x = 66. ......... (2)

Now, doing [(2)*2] - (1),

Means, multiplying equation (2) by 2 and subtractin equation (1) from it,

12y + 8x = 132

-7y - 8x = - 87
_________________

5y = 45

Or, y = 45/5 = 9.

And, now putting y = 9,

7(9) + 8x = 87

Or, 8x = 87 - 63 = 24

Or, x = 24/8 = 3.

$<b>$ ➡️ Hence,

Cost of 1 pen (y) = Rs. 9

Cost of 1 pencil (x) = Rs. 3

$<i>That's it.. </i>$
$</b>$
$<marquee>$
☺️ ${\huge {\mathfrak {\red {Happy \: Birthday \:, Sneha}}}}$ ☺️
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${\huge {\mathbb {\green {Thanks}}} }$