Question

There are nine water bottles in a fridge. Three full boxes are added. Two more boxes are added, both of which have one fewer bottle than the other three. There are now 67 bottles in the fridge. Write and solve an equation to find the number of bottles in a full box.

Answer 1

The number of bottles in a full box is 12.

Explanation

Suppose, the number of bottles in a full box is  $x$

So, the number of bottles in three full boxes $=3x$

Now, two more boxes are added, both of which have one fewer bottle than the other three. So, the number of bottles in these two boxes $= 2(x-1)$

As there were 9 bottles initially and now there are 67 bottles in the fridge, so the equation will be....

$9+3x+2(x-1)=67\\ \\ 9+3x+2x-2=67\\ \\ 5x+7=67\\ \\ 5x=67-7\\ \\ 5x=60\\ \\ x=\frac{60}{5}=12$

Thus, the number of bottles in a full box is 12.