Calculate the area of the shapes below ( I need help fast)

What is the area of a rectangle with vertices (-8,-2), (-3,-2), (-3,-6), and (-8,-6)? units

Ineed here’s a picture of the question

The floor of a building consists of 3000 tiles which are rhombus shaped and each of it's diagonals are 45 cm and 30 cm in length. find the total cost of polishing the floor, if the cost per m² is rs. 4.