Subtraction gives you the difference between two quantities.

• There were 10 fish, but 5 flew away. How many are left?
• There are 5 cupcakes at a party, and 4 guests. Each guest ate one cupcake, how many are left?
• There are 20 people with 50 slices but only 20 them ate. There are 30 slices left over after the party