Question

If 5 pens cost Rs.25, find graphically how many pens can be bought for Rs. 35. Also, find the cost of 3 pens.
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Answer 1

Answer:

Let cost of one pen = x

cost of one pencil = y

5 pens and 6 pencils cost Rs. 9

⇒ 5x + 6y = 9 ....................(1)

⇒ 5x = 9 - 6y

⇒ x = (9-6y)/5

3 pens and 2 pencils cost Rs 5

⇒3x + 2y = 5

⇒3(\frac{9-6y}{5}

5

9−6y

) + 2y = 5

⇒\frac{27}{5} - \frac{18y}{5} +2y = 5

5

27

−

5

18y

+2y=5

⇒27 -18y +10y = 5*527−18y+10y=5∗5

⇒27 -8y = 2527−8y=25

⇒ \begin{lgathered}-8y = 25-27 =-2 \\ y =(-2)/(-8) = 0.25\end{lgathered}

−8y=25−27=−2

y=(−2)/(−8)=0.25

x =

Cost of one pen = Rs. 1.5

Cost of one Pencil = Rs. 0.25

So cost of one pen and one pencil = 1.5+0.25 = Rs 1.75

Answer 2

cost of 5 pen = rs.25

cost of 1 pen =25/5

=5rs

pens can be bought for rs.35=35/5

=7pens

cost of 3 pens =3*5

=15rs