Daniel has 5 pencils in a cup. He takes some pencils out. There are 2 pencils left in the cup. Find the number of pencils he has taken out.
Emma built 7 sandcastles on the beach. The tide came in and washed some of them away. There are 2 left and she wants to know how many were washed away.
Which of these number sentences does she need to solve?
Which of these addition facts can help her solve the problem?
How many sandcastles were washed away?
Given that , what is ?