2 step number problems

There were 11 books on a shelf and 12 books on another shelf. 7 books were taken by some children to read.  How many books were left on both shelves?

 

A box of pencils holds 10 pencils when full. There are 2 full boxes of pencils.  11 pencils are then taken away to be used.  How many pencils are left?

 

There are 12 sheep, 13 cows and 4 goats in a farmyard. How many animals are there altogether?

 

There are 15 footballs in one bag and 5 footballs in another bag. 6 balls are used for practice.  How many balls are not used?

 

There are 10 people in a room and 16 people come to join them. 7 people then leave.  How many people are left in the room?