Percentages are ratios of an amount compared to 100. The percent change of an old to new value is equal to 100% x \({ new - old \over old }\).
The total water usage for a city is 30,000 gallons each day. Of that total, 31% is for personal use and 61% is for industrial use. How many more gallons of water each day is consumed for industrial use over personal use?
| 4,550 | |
| 2,500 | |
| 9,000 | |
| 6,800 |