Question

Cost of 7 pens and 8 pencils is ₹87 and cost of 6 pens and 4 pencils is ₹66. Write

the linear equations representing the above data and draw its graph. Also find the

cost of 1 pen and 1pencil from the graph.

pls answer as soon as possible.​

Answer 1

Answer:

7y + 8x = 87

6y + 4x = 66

Step-by-step explanation:

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 subtracting 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.

 Hence,

Cost of 1 pen (y) = Rs. 9

Cost of 1 pencil (x) = Rs. 3

hope it helps !

Answer 2

Step-by-step explanation:

let cost of one pen be x and cost of a pencil be y

so, according to first situation

7x+8y=87. -1

according to second situation

6x+4y=66. -2

subtract eq. 2 from 1st

So, 7x+8y-6x-4y = 87-66

x+4y =21

x= 21-4y. -3

replacing value of x in eq. 1

7(21-4y)+8y =87

147-28y+8y =87

147-20y=87

147-87=20y

60=20y

60/20=y

3=y

so x= 21-4×3

x=9