Question

if a number decreases from 1,000 to 805 what is the rate of decrease?

Answer 1

do we have a time?

Answer 2

there is no rate of decrease, but there is an amount of decrease. To have a rate, you must have a time...

If you want to find the percentage change from A to B, calculate:

\[\frac{B-A}{A}*100\%\]

Positive result means increase, negative result means decrease.

For example, going from 10 to 8:
\[\frac{8-10}{10}*100\%= -20\%\]
Going from 8 to 10:\[\frac{10-8}{8}*100\% = +25\%\]