Question

The price of an item is reduced by 10% followed by a reduction of 20%, then the resulting reduction is: a) 30% b) 12% c) 21% d) 28%

Answer 1

say something costs x dollars and you reduce it by 10%
that means you subtract off 10% of x
x - 10% of x

write 10% as the decimal 0.10
x- 0.10 x
factor out the x
x(1-0.10)
simplify 1-0.10 to get 0.9
x*0.9 or

0.9 x

in other words, 10% off means multiply by 0.9

Answer 2

20% off means "multiply by 0.8"

so if you take off 10%, to get 0.9x
then take 20% off of that: 0.8*0.9*x
and simplify you get
0.72 x

Answer 3

so 28% thank you boss.
you are the best