Given the value $690$, I want to remove $10$% from that and then remove another $20$% from the resulting value, so as an example, I am doing:
$690 \over {(1 + 0.1 + 0.2})$ = $690 \over {1.3}$ = $530.76.$ Apparently, I was told this is wrong and it should be:
$690 * 0.9 =$ $621 \over {1.2}$ = $517.50$
In the above, the $10$% is non-compounded and the $20$% is compounded. Can someone explain what is the difference between the $2$ and is one way better than the other if I do not know certain values like the start or end value (690 in this case)
If I do $690 \over {1 + 0.111111111111 + 0.2}$, I get closer to $517.50.$