Question

I will give braniest

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.

Write the equation

Answer 1

9 + 3b + 2(b-1) = 67
Where b stands for the number of bottles in a full box
(9 bottles + 3 full boxes + 2 (full boxes -1 bottle) = a total of 67 bottles)

To solve, we can expand the brackets
9 + 3b + 2b -2 = 67
And collect like terms
7 + 5b = 67
Minus 7 from both sides
5b = 60
Divide by 5
b = 12