Answer:
20 - (4 + 2)
Step-by-step explanation:
The original amount is 20.
The number of cookies left is the original amount minus the amount that was eaten.
Amy ate 4 cookies.
Her brother ate 2 cookies.
Amount that was eaten: 4 + 2
Amount left = original amount - amount that was eaten
amount left = 20 - (4 + 2)
