1.25 is the length x of a side of the square. Think about it like this. Divide 25 by 16 and you get 1.5625. Then, you do that number squared. So, √1.5625. That gives you 1.25. Hope that helps! Good luck!
He needs 6 litres of the 20% and 2 litres of the 60% a simple trial and error method will do in this type of equation
In geometry, a hexagonal pyramid is a pyramid that has a hexagonal bases which are erected six triangular faces.