Question

The total cost of 5 pens and 10 pencils is Rs. 30. If a pen costs Rs. 3 more than a pencil, find the price of each item.

Answer 1

cost of a pencil = x
cost of pen = x+3
10x + 5(x+3) = 30
10x + 5x + 15 = 30
15x = 15
x = 1
cost of pencil = 1
cost of pen = 1+3 or 4

Answer 2

let cost of pen=x cost of pencil=y
then 5x+10y=30
and x=3+y => subtituting in the first equation
5(3+y)+10y=30
15+15y=30
15y=15
y=1
x=3+y => x=3+1=4

cost of pen =4 cost of pencil =1