A school buys stationery items for different classes. The algebraic expressions representing the purchases are:
Class \(7\) buys \(3x + 7y + 10z\)
Class \(8\) buys \(7x - 4y + 13z\)
Where \(x\) represents the number of notebooks, \(y\) represents the number of pens and \(z\) represents the number of geometry boxes.
1. The total number of stationary items bought by the school is
2. The difference between class\(7\) and \(8\) purchase is
3. What is the total number of stationary items bought by class \(7\) if \(x = 1\), \(y = 5\) and \(z = 1\).
4. If Class \(8\) returns \(x + y\) items, then the new expression is