Question

A set of 3 pens and 4 pencils cost rs 19.50 but a set of 4 pens and 3 pencils cost rs 21.50 . Then what the cost of a pen and what is the cost of a pencil

Answer 1

Step-by-step explanation:

let the cost of pen =x

cost of pencil=(19.50-x)

the cost of 1pen =x/3

the cost of 1pencil =(19.50-x)/4

let the cost of pen =x

the cost of pencil=(21.50-x)

the cost of 1pen=x/4

the cost of 1pencil=(21.50-x)/3

now,according to question,

x/3+(19.50-x)/4=x/4+(21.50-x)3

taking LCM both sides,

4x+3(19.50-x)/12=3x+4(21.50-x)/12

both denominator are cancelled by each other,

4x+58.5-3x=3x+86-4x

x+58.5=-x+86

x+x=86-58.5

2x=27.5

x=27.5/2

=13.75

the cost of 3 pens =13.75

and the cost of 4pencils =19.50-13.75