Last week’s answer: 25cm. If 6 bricks are 10cm high, then 3 bricks are 5cm high. This means the tower will be 5 x 5 = 25 cm tall, as there are 5 lots of 3 bricks in 15 bricks.
This week’s problem: The perimeter of a rectangle is 18cm and its area is 20cm^2. How long are the sides of this rectangle?
The answer will be in next week’s weekly problem.