Question

Brian and Zack went to the store and bought packs of gum. Brian bought 3 less packs than twice the number zack bought. Together they bought a total of 30 packs of gum. How many packs did each of them buy?

Answer 1

• Zack: 11
• Brian: 19

Explanation:

Let z and b represent the number of packs that Zack and Brian bought, respectively. Then the problem statement tells us ...

b = 2z -3 . . . . . . . Brian bought 3 fewer than twice what Zack bought

b + z = 30 . . . . . . they bought a total of 30 packs

Using the first equation to substitute into the second, we have ...

(2z -3) +z = 30

3z -3 = 30

3z = 33 . . . . . . add 3

z = 11

b = 2·11 -3 = 22 -3 = 19

_____

Check

b + z = 19 + 11 = 30 . . . . answer checks OK

Zack bought 11 packs; Brian bought 19 packs of gum.