Question 252979
Perimeter is 10 plus 8 times 2 or 36 metres. This is 360 decimetres.
Divide by 4 and we have 90 plants.
Think of this unwrapped, it is 36 metres long. In each 0.4 metre unit you can plant 1 bush. If you plant it in the middle you have 90 bushes with 0.2 metres each side.
Another way to think of it is how you would plant a straight line. for a straight 0.4 metre line you could plant 2 bushes, one at each end. So a 10 metre side could have One at the start, one every 0.4 metres and ONE AT THE END. This is the one you are trying to discount, but you don't have to, you haven't added it in.
Think also of the fence. You need two posts to hold 1 fence, but here we are counting fences, NOT posts. Hope this helps