diagonal bridge help

Hi im literally sat here in tears because i’ve been here for hours trying to recreate the bridge in this image but i can’t do it and all the tutorials aren’t helping me at all. i think it’s cus im really stupid like i failed math and this involves slight math so im just too stupid to understand it all and it’s getting me upset lol. like all the videos i watch aren’t trying to place the bridge in that exact position and im too stupid to try and change the tutorial in my head to fit a bridge facing left instead of right. does anyone have a tutorial that’s really simple? or one that’s in the exact position im trying to do as in it’s facing left