Question

There are nine water bottles in​ Devin's refrigerator. He adds three full boxes of water bottles to the refrigerator. Then he adds two more boxes that each has 1 fewer bottle than a full box. When he is​ done, there are 67 bottles in the refrigerator. Write and solve an equation to find the number of bottles in a full box.

Answer 1

9+3x+2(x-1)=67

x=12

Explanation:

So we have 9 water bottles, so we put that as 9 in our equation. Then he adds 3 full boxes of water bottles, but we don't know how many water bottles are in each box, so we would label that as x, so it would be 3x. Then he adds two more boxes that each has 1 fewer bottles than a full box, so that would be 2(x-1) because we know that each box has x amount of water bottles, and you just subtract one, and we also know that we have 2 of those boxes. Then, when he is done, that means the whole equation equals, 67. Our equation would be 9+3x+2(x-1)=67. Now we solve for x.

9+3x+2x-2=67

9+5x-2=67

9-2+5x=67

7+5x=67

5x=60

x=60/5

x=12

Answer 2

12

Explanation:

let x be 1 full box

9 + 3x + 2(x -1) = 67

67 - 9 = 58

3x + 2(x -1) = 58

expand 2 into the bracket

3x + 2x - 2 = 58

5x = 60

x = 12