Question

The cost of 2 pens and 3 erasers is Rs 46.the cost of pen and 2 erasers is Rs 26.find the cost of 4 pens and 4 erasers

Answer 1

let pens = x 
   erasers = y 

2x+3y=46   (1)
 x+2y=26     (2)
subtract equations
x+y=20 
x=20-y    (3)
put (3) in eq 2
20-y+2y=26
y=26-20
y=6
put value of y in eq 3
x=20-6=14
cost of 4x and 4y
4*14+4*6
=56+28=84