If the discount is both $68.00 and 40%, we can set this up as an equation.
40% = $68.00
The sides have different units but we can still use regular algebraic rules, such as multiplication or dicvision on both sides by the same number, provided said number does not have units ( or even if it does, we would just have to change the units appropriately in the equation.
The original price would be 100%, which is 40% * 2.5 so,
2.5(40%) = 2.5($68.00)
You can also confirm this answer by dividing the discount in dollars by 40, giving a one percent price, and then multiplying by 100 to get the full price. Some people find this method more intuitive, but really it is the same thing just with an extra step.