Reasoning and answer: First find how many ml of water Jason needs for 1 gram of charcoal: 30 ml / 2 grams = 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 = 60 g.
The answer: 60
What was the question?
Question: 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?

Reasoning and answer: The first movie was 2 * 60 = 120 minutes. So this movie is 120 * .6 = 72 minutes longer. So this movie is 192 minutes. It also cost 50 * 2 = $100 per minute to film. So it cost 192 * 100 = $1920.
The answer: 1920
What was the question?
Question: Janet filmed a new movie that is 60% longer than her previous 2-hour long movie. Her previous movie cost $50 per minute to film, and the newest movie cost twice as much per minute to film as the previous movie. What was the total amount of money required to film Janet's entire newest film?

Reasoning and answer: Noah earned $60 / large painting x 8 large paintings = $480 for the large paintings. He also earned $30 / small painting x 4 small paintings = $120 for the small paintings. His total sales last month were $480 + $120 = $600. So, his sales this month are $600 x 2 = $1200.
The answer: 1200
What was the question?
Question:
Noah is a painter. He paints pictures and sells them at the park. He charges $60 for a large painting and $30 for a small painting. Last month he sold eight large paintings and four small paintings. If he sold twice as much this month, how much is his sales for this month?