The student is correct. Due to the meaning of perimeter which is all sides added up to make a number total, it is possible for a square and a rectangle to have the same perimeter if the numbers add up.
Find the area of the rectangle. You can find the area of a rectangle with the following formula:

w = width, and l = length.
Plug in your width and length:

The area of the rectangle is 200 square centimeters.
The area of a square is also given by width * length. Multiply the sides together:

The area of a square is 4x^2.
Because you're cutting away the square from the rectangle, you will subtract the area of the square from the area of the rectangle. The following equation will be your answer:
7 to 4 is the ratio of salsa jars to salsa bags
The actual trees should be planted 43 ft apart