Expression 1; If your friend bikes 1.5 miles home from school each day for 4 weeks, they bike a total of - miles in that time period. The math I did was multiply 5 by 4 to get 20 school days in 4 weeks, and multiplied 1.5 by 20 to get 30 miles biked in 4 weeks.
Expression 2; If you bike 3.25 miles home from school each day, using the same math shown in the previous expression, substituting 1.5 for 3.25. Using that math, you would bike 65 miles in 4 weeks.
Sarcastic conclusion; You and your friend both get quite the leg day just to get home from school!