Jason is mixing a batch of black paint. He needs to add 2 grams of charcoal for every 30 ml of water. If he adds 900 ml of water, how much charcoal does he add?
First find how many ml of water Jason needs for 1 gram of charcoal: 30 ml / 2 grams = <<30/2=15>>15 ml/g
Then divide the amount of water Jason uses by the amount of water per gram of charcoal to find how much charcoal he uses: 900 ml / 15 ml/g = <<900/15=60>>60 g
#### 60