It takes 200 pieces to pave the floor of the study with 15cm long square bricks. How many pieces do you need to use 25cm long square bricks instead?
15x200x15 = 45000 square centimeter
45000 / (25 * 25) = 72 pieces
You need 72 yuan for the 25cm side
2 use the equation to set X blocks with side length of 25cm
15*15*200=25*25*x
X = 72
You need 72 yuan for the 25cm side