Question

Five pens and four pencils cost $2.55. But four pens and five pencils cost $2.40. How

much do the pens cost and how much do the pencils cost?

Answer 1

pens: $0.35, pencils: $0.20

Explanation:

pens=x

pencils=y

5x+4y=255 --> 5x=255-4y --> x = 51 - 4y/5

4x+5y=240

4(51-4y/5) + 5y = 240

204 - 16y/5 + 5y = 240

5y - 16y/5 = 36

25y - 16y = 180

9y = 180

y = 20 cents = $0.20

x = 51 - 4(20)/5

x = 51 - 16

x = 35 cents = $0.35

Answer 2

1*5=12.75

2*4=9.6

so nine pens cost 3.15

one pen will be 0.35$

so one pencil will be .20$