Question

what single discount is equal to a discount of 1/4 off followed by an additional 30%off the sale price ?

Answer 1

original selling price --- x

after 1st discount ----- (3/4)x
after 2nd discount ----- (7/10)(3/4)x
= 21/40 x
21/40 = .525 = 52.5 %
so a single discount of 47.5% would do the same thing

illustration:
suppose an article sells for $120
after the first discount: 120 - (1/4)(120) = 90
30% off that is $ 27 for a final sale price of $63

single discount of 47.5% ---> 120(.475) = 57
final price = 120 - 57 = 63
my answer is correct