The equation for this question.

A company bought 34 boxes of cookies for a total of $130. The boxes of cookies cost either $3 per box (for one brand) or $5 per box (for a different brand.) How many of the $3 boxes did the company buy?

We can solve this by setting up a system of equations. We will use x for the $3 boxes and y for the $5 boxes:

x+y=34

3x+5y=130

We can use the elimination method by multiplying the first equation by 3:

3x+3y=102

3x+5y=130

0x-2y=-28

y=14

We can then plug this number back into one of the original equations to solve for x:

x+14=34

x=20

We can check these answers by plugging them into the equations:

20+14=34

34=34

(3) (20) + (5) (14) = 130

60+70=130

130=130

Therefore, there are 20 of the $3 boxes, since we originally said that x would be the $3 boxes.