You need a 30% alcohol solution. On hand, you have a 50 mL of a 20% alcohol mixture. You also have 35% alcohol mixture. How much of the 35% mixture will you need to add to obtain the desired solution?

The architect's side view drawing of a saltbox-style house shows a post that supports the roof ridge. the support post is 8 ft tall. the distance from the front of the house to the support post is less than the distance from the post to the back of the house. how far from the front of the house is the support post positioned?