In a class of pupils, 4 play the flute and piano, 15 play the flute only.
8 play the piano only.
12 play neither instrument.
How many pupils are in the class?

Similarly fie each expression 18,19,20

Ken leaves work 20 minutes late. he decides to make up time by taking the toll road instead of side streets. he can travel three times faster by taking the toll road. create an equation to represent his total travel time, including wait time, where x is the number of minutes the drive was expected to take

Each weekday davina rides her bike from her house to school. after school, she rides to the library. then davina takes the same route to get home. these locations are shown on the grid below, where 1 unit on the grid represents 1 kilometer. how many kilometers does she ride each day? 10 16 20 32