Hey there! :D
Think of it this way. The garden is a rectangle. We are trying to find the area of the walk way (that is like a line) around the rectangle. We know area= length*width.
We have the dimensions of the rectangular garden. 3 ft* 5 ft. This means that two sides of the rectangle is 3 ft long, and the other two are 5 ft long. We know the width of the side walk already. (which is 2)
Area= length*width
A= 5*2= 10 (for one side)
10*2= 20
A= 3*2= 6 (for one side)
6*2= 12
20+12= 32
The area of the walkway will be 32 ft^2.
I hope this helps!
~kaikers