You will work with the data below. This data is stored in the store variable.

Item	Price	Sold
Sofa	340	67
Armchair	150	81
Dining table	115	79
Bookshelf	160	42
Kitchen Cabinet	70	67

Your tasks are:

1. Add a new column named 'Revenue' with the revenue of each item (multiply 'Price' and 'Sold'). To access columns, use the $ sign.
2. Using the sum() function, calculate the total number of items sold. Save in items_sold variable and output its value.
3. Calculate total revenue using sum() function. Save in the total_revenue variable and output its value.
4. Find out the average price of the sold item - divide total_revenue by items_sold.