There were 15 birds in the park. Some (n) of them flew away. Which expression could be used to figure out how many birds are still remaining in the park?

Roula had 117 gumballs. Amy had x less than 1/2 the amount that Roula had. Which expression shows how many gumballs Amy had?

Andrea went strawberry picking. She picked 245 strawberries. Julio went with her and picked x fewer than she did. Which expression shows the number of strawberries that Julio picked?