Pi is the ratio of the area of a circle to its diameter.
Think about it this way, what is 5x3??? 15 right. Ok then what is 5x30???? 150. So the store should sell each soccer ball for $5 each:)
You want 125 pounds minus 4% of it, so you want 96% just multiply it
125 . 96% = 125 . 96/100 = 120