Explanation:
x = original price
first I show you the line of thinking and why the short approach at the end would work.
100% = x
1% = 100%/100 = x/100
25% = 1% × 25 = x/100 × 25 = x/4
but careful, these 25% are not the sale price, they are only the discount.
so, the sale price is actuality 100% - 25% = 75% of the original price.
so, we need actually
75% = 3×25% = 3x/4
and now we can solve :
40 = 3x/4
3x = 160
x = 160/3 = 53.333333... ≈ $53.33
FYI - the short, direct method is simply to divide by the percent factor.
x = 40 / 75/100 = 40/0.75 = 53.333333...
if you compare it with the long form and think it through, you will see why this works.
let me know if you need any further explanations.