Stephen H. answered • 11/24/20

Tutor of Math, Physics and Engineering ... available online

... can't post graphs but consider this ... x +y =5 (from the narrative) ... if BS=books in a small box = 25 and BL = 50, then xBS+yBL=200 total books sent. Rearranging the x+y= 5 to y= 5-x is a line from x=0 and y=5 to y=0 to x=5. Rearranging the second yields y=4-x/2 (BS=25 and BL=50) and is a line from x=0 and y=4 to x=8 and y=0. The intersection of these two lines is at x=2