If the recipe originally serves 3 portions and we require the amount of each ingredient that is needed to make 2 portions, simply multiply each amount in the original recipe by 2/3.
The preimeter is adding all sides together. I took 154-55 twice sense we have four sides of a rectangle and two are lengths. after that i got 44. I then just remembered we had two sides left so divided that by 2 and got 22