If you let x = the original amount, then an increase of 33.33% would be represented by
x + (x × 33.33%)
Then if there was a decrease of 50%, you would now have
[x + (x ×33.33%)] × 50%
rewrite with decimal instead of %
[x + (x × .3333)] ÷ 2
The brackets and parentheses are important to tell the order in which to proceed.
