A barrel of water is full. It decreases by 85%. Now it has 120 liters of water. How much liters of water did it have to begin with?
In order to find the original amount of water, we divide the amount given by its corresponding percentage, in this case 15% (because if 85% of water is gone then 15% remains).
If x represents the original amount of water, then:
120 = (0.15)x
x = 800
There was originally 800 liters of water
