Manuel wants 30 liters of a mixture of water and 10% lemon juice. He has a mixture of 8% lemon juice and a mixture of 20% lemon juice. How many liters of the 8% and 20% mixtures should he mix to get what he wants?

Acone is placed inside a cylinder. the cone has half the radius of the cylinder, but the height of each figure is the same. the cone is tilted at an angle so its peak touches the edge of the cylinder’s base. what is the volume of the space remaining in the cylinder after the cone is placed inside it?