Question

1. 5 pens and 6 pencils together cost Rs. 9.00. and 3 pens and 2 pencils cost Rs. 5.00. Find the cost of 1 pen and 1 pencil.

Answer 1

here my friend you answer is Rs. 1.5 for one pen and Rs. 1.00 for one pencil.

Answer 2

Given

• 5 pens and 6 pencils together cost Rs. 9.00 .and 3 pens and 2 pencils cost Rs.5.00 . find the cost of 1 pen and 1 pencil. 

To Find

• Find the cost of 1 pen and 1 pencil. 

Solution

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

$⇒3(\frac{9-6y}{5}59−6y ) + 2y = 5$

$⇒\frac{27}{5} - \frac{18y}{5} +2y = 5527−518y+2y=5$

⇒27 -18y +10y = 5×527−18y+10y=5×5

⇒27 -8y = 2527−8y=25

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

x = (9-6y)/5 = (9-6(1/4))/5 = 7.5/5 = 1.5(9−6y)/5= (9−6(1/4))/5=7.5/5=1.5

• 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