Since there are 2 sides to the shelf, there is 0.05*2=0.05+0.05=0.1 meters of space between the shelf and wall in total. Next, since each piece of wood is 0.3 meters wide and we have 3 of them, the total width of the wood is 0.3+0.3+<something>
Note that <width of wood>+<space between shelf and well> =width of closet
I challenge you to finish this on your own - good luck, and feel free to ask with any further questions!
