Question

$X$ has pens and pencils which together are $40$ in number. If he had $5$ more pencils and $5$ less pens, the number of pencils would have become $4$ times the number of pens. Find the original number of pens.

• A. $10$
• B. $11$
• C. $12$
• D. $13$

Answer 1

The correct option is D $13$

Let the number of pens be $x$ & the number of pencils be $y$.

Then by the first condition, $x+y=40$ ...........(i)

And by the second condition, $y+5=4(x-5)$

$\Rightarrow y=4x-25$ ...........(ii)

Comparing (i) & (ii),

$4x-25=40-x$

$\Rightarrow 5x=65\Rightarrow x=13$

So, the original number of pens $=13$