Question: I'm completely lost with this math problem: A hand-painted wallpaper costs $400 at the market. A DIY will saves 20% after considering the materials cost. If Ethan made his own hand-painted wallpaper, how much was the total cost?
Can you give me a hand?
Answer: 
A DIY will saves 20% after considering the materials cost, meaning you will save 20/100*$400=$80 if you make your own hand-painted wallpaper.
The total cost of a hand-painted wallpaper made at home is $400-$80 = $320