5 pens and 6 pencils together cost ₹ 9 and 3 pens and 2 pencils cost ₹ 5. Find the cost of 1 pen and 1 pencil.
Given:
5 pens and 6 pencils together cost ₹ 9 and 3 pens and 2 pencils cost ₹ 5.
To do:
We have to find the cost of 1 pen and 1 pencil.
Solution: 
Let the cost of one pen and one pencil be $x$ and $y$ respectively.
According to the question,
$5x + 6y = 9$.....(i)
$3x + 2y = 5$.....(ii)
Multiplying equation (ii) by 3 on both sides, we get,
$3(3x+2y)=3(5)$
$9x+6y=15$.....(iii)
Subtracting equation (iii) from equation (i), we get,
$(9x+6y)-(5x+6y)=15-9$
$9x-5x+6y-6y=6$
$4x=6$
$x=\frac{6}{4}$
$x=\frac{3}{2}$
Substituting $x=\frac{3}{2}$ in equation (ii), we get,
$3(\frac{3}{2})+2y=5$
$\frac{9}{2}+2y=5$
$2y=5-\frac{9}{2}$
$2y=\frac{5\times2-9}{2}$
$2y=\frac{1}{2}$
$y=\frac{1}{2\times2}$
$y=\frac{1}{4}$
$x=1.5$ and $y=0.25$
The cost of a pen is Rs. 1.50 and the cost of a pencil is Rs. 0.25.
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