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

(d) 13

Let the number of pencils and pen with X be x and y respectively,

Given,  x + y = 40 ........(i)

Also (x + 5) = 4(y – 5)

\(\Rightarrow\)x + 5 = 4y – 20

\(\Rightarrow\) x – 4y = –25  ......(ii)

Subtracting eqn (ii) from eqn (i), we get

5y = 65

\(\Rightarrow\) y = 13.