## Elementary Algebra

We consider the width of the box as $x$ centimeters. Therefore, three times the width is $3x$ cm. Since the length ($34$ cm) is $4$ centimeters more than three times the width, we write the following equation and solve: $34-3x=4$ $-3x=4-34$ $-3x=-30$ $x=\frac{-30}{-3}$ $x=10$ Therefore, the width is 10 centimeters.