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Form the pair of linear equations in the following problems, and find their solutions graphically. (ii) 5 pencils and 7 pens together cost Rs 50, whereas 7 pencils and 5 pens together cost Rs 46. Find the cost of one pencil and that of one pen.

Q1.    Form the pair of linear equations in the following problems, and find their solutions graphically.

                    (ii) 5 pencils and 7 pens together cost Rs 50, whereas 7 pencils and 5 pens together cost Rs 46. Find the cost of one pencil and that of one pen.

Answers (1)
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Let x be the price of 1 pencil and y be the price of 1 pen,

Now, According to the question

5x+7y=50......(1)

And 

7x+5y=46......(2)

Now, The points (x,y), that satisfies the equation (1) are 

X 3 -4 10
Y 5 10 0

And, The points(x,y) that satisfies the equation (2) are 

X 3 8 -2
Y 5 -2 12

The Graph,

Graph

As we can see from the Graph, both line intersects at point (3,5) that is, x = 3 and y = 5 which means cost of 1 pencil is 3 and cost of 1 pen is 5.

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