The greatest that you can decrease most items is 100%.
If you decrease an item by 100%, it then disappears.
However, if you can have a negative answer, then do this:
Find 145% of 84 -- which is 1.45 x 84 or 121.80
Subtract this amount from the original amount: 84 - 121.80 = -37.8
Note: to find 145% of 84:
to change 145 into a decimal, divide by 100, which moves the decimal point two places to the left
interpret the word "of" as times
So, 145% of 84 becomes 1.45 x 84