For a big cleaning job, Tyler wants to mix some ammonia-based cleaners to get a certain concentration of ammonia. He has 4 gallons of cleaner that is 18% ammonia. He also has a
large supply of cleaner that contains 8% ammonia. How many gallons of the 8%-ammonia
cleaner does Tyler need to add to the 18% ummonia cleaner to obtain a batch that contains
15% ammonia?
Write your answer as a whole number or as a decimal rounded to the nearest tenth.
gallons