The document provides a 3-step process to calculate how much cash in $10 bills can fit in a 30-liter backpack. It determines that 250,000 dollars worth of $10 bills, or 25,000 bills, would have a volume of 26,250 cubic centimeters and would fit in the 30-liter backpack. The steps include: 1) calculating the number of $10 bills from the total amount, 2) determining the height of one bill, and 3) using the bill dimensions to calculate the total volume of all the bills.