Sagot :
Answer:
30-2x cm
Step-by-step explanation:
It depends in the dimension of the square.
Let's say the side is going to be x.
The length of the box would be 30 - 2x cm.
Example:
If you are going to take out a square of side 3cm, you are going to cut 3cmx3cm from left and from right. So length 30cm now would decrease to 30 - 3*2 cm = 24cm.