Question

what single discount is equalent to two successive discount of 25% and 5%

Answer 1

x + y - (x × y) / 100

25 + 5 - (25 × 5) / 100
30 - 1.25
28.75

Answer 2

Formula=
$- x - y + \frac{xy}{100}$
$- 25 - 5 + \frac{25 \times 5}{100}$
$- 30 + \frac{5}{4}$
$\frac{ - 120 + 5}{4} \\ \frac{ - 115}{4} \\ - 28.75$
One single discount equivalent to two successive discounts of 25%, 5% is 28.75%