((y2 - y1) / y1)*100 = your percent change. y1 is the original value, and y2 is the value it changed to.

Using the formula for percentage change, and following the order of operations

- Subtract (2.50 - 9.49) which gives you: -6.99
- Divide -6.99 / 9.49 which gives you: -0.7365648050
- Multiply -0.7365648050 * 100 = -73.6564805