Decrease £680 by 10%

Two ways to do it.

1

if we decrease 10%, then we'll have the 90% of the original, so we have:

= 680 (90%)

= 680 (90/100)

= 612

then 612 is 680 decreased by 10%

2

what is the 10% of 680, call it y?, then reduce it from 680

y = 10% (680) = (10/100) (680) = 68

So, to decrease 680 by 10%, we subtract 680 - 68 = 612