Question

Peter is buying office supplies. He is able to buy 3 packages of paper and 4 staplers for $40, or he is able to buy 5 packages of paper and 6 staplers for $62. How much does a package of paper cost? How much does a stapler cost?

Answer 1

paper = $4 and stapler = $7

Explanation:

let p represent paper and s represent stapler, then

3p + 4s = 40 → (1)

5p + 6s = 62 → (2)

Multiplying (1) by 5 and (2) by - 3 and adding will eliminate p

15p + 20s = 200 → (3)

- 15p - 18s = - 186 → (4)

Add (3) and (4) term by term to eliminate p

2s = 14 ( divide both sides by 2 )

s = 7

Substitute s = 7 into either of the 2 equations and evaluate for p

Substituting into (1)

3p + 4(7) = 40

3p + 28 = 40 ( subtract 28 from both sides )

3p = 12 ( divide both sides by 3 )

p = 4

Thus package of paper costs $4 and stapler costs $7