Let’s look at it like this, Mr Woodstock has a plot of land and he wants to put a fence around his plot, from the question we know two sides of his plot are one being 36 meters long and the other 16 meters long. So if he wants to fully surround his land he will need enough for all four sides both long sides and both wide sides so it’s as simple as 36 + 36 + 16 + 16 = 104 meters, If it helps I like to drop the sixes and just add the 30+30+10+10 to get 80 then add the four sixes together 6+6+6+6 which gives 24 then add the two together 80+24=104 that way you don’t have to worry about making sure to carry the one or anything like that, just helps me do math in my head faster, hope this helps!