The amount of water in a bottle is reduced by 85% to 20 milliliters. How much water was originally in the bottle?

To find the original quantity when given the percent it was reduced and the amount left, divide the amount left by the percentage that is left:

The bottle was reduced by 85%, which means there is 15% left left in the bottle (100% - 85% = 15%)

Now divide the amount left by the percentage left:

20 / 0.15 = 133.33

The original amount was 133.33 milliliters (Round answer as needed)