The solution would be like this for this specific problem:
Given:<span>
25% discount</span>
Hasan: d - 0.25d<span>
Bella: 0.75d</span>
d = original price.<span>
0.25d = discount.
0.75d = discounted price.</span>
Let’s say the price of the book is $1,000.
0.25d = 0.25(1000) = 250 <span>
0.75d = 0.75(1000) = 750</span>
d - 0.25d = 1000 - 250 = 750
<span>0.75d = 0.75(1000) = 750</span>