the cost of a pen is three times the cost of a pencil. the cost of 4 pencils and 3 pens is $9.75. what is the cost of a pencil?

Question

the cost of a pen is three times the cost of a pencil. the cost of 4 pencils and 3 pens is $9.75. what is the cost of a pencil?

Answer 1

Let x=cost of pen

Let y = cost of pencil

 

1)  x = 3y      pens cost 3 times as much as pencils

2) 3x+4y = 9.75   3 pens and 4 pencils cost $9.75

 

substitute 3y in place of x in 2nd equation to solve for y

 

3(3y) + 4y = 9.75

9y + 4y = 9.75

13y = 9.75

y = 9.75/13

y = $0.75

 

Pencils cost $0.75

 

Answer 2

pencil: 0.75

pen: 2.25