In your own words ,explain when you use usted and when you use tu

Based on the information in the text and what you learned from the lesson what cultural practice is this text referring to

How has roman culture influenced western civilization

Achemist mixes 4 liters of one acid solution with 10 liters of a 40% solution, resulting in a 30% acid solution. what is the value of x, the acid concentration of the first solution