There are a number of preposition words that change the meaning of a phrase when used with a particular word. For example, you can use Reduce with different prepositions, and you will get a different meaning every time. You can see the examples below:
1. Reduce to
Reduce to (To decrease)
Example: His salary was reduced to Rs Four thousand only.
2. Reduce by
Reduce by(decrease by an amount)
Example: His salary was reduced by three hundred per month.