Answer:
I think you meant 40% off. If so...
Explanation:
First, you have to turn 40 into a decimal - .40.
Then you multiply 30*.40 and get 12.
Subtract 12 from 30 since you are saving 12 dollars.
This means you spend $18 and saved $12.
So, your final answer would be $12.
Hope this helps :)