What is biggest to smallest unit out of kg, grams, ounces and pounds?

Which of the following answers is 7/9 simplified? 7/9 2/9 11/9 2/7

1) prove that 731^3−631^3 is divisible by 100 2) prove that 99^3−74^3 is divisible by 25

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.