Final answer:
The question covers a variety of mathematical problems related to arithmetic and algebra, likely for high school students, involving operations like mean calculation and solving equations.
Step-by-step explanation:
The question involves mathematical calculations and appears to be a series of unrelated math problems or exercises that might be part of a homework assignment for a high school level math class. The examples involve basic arithmetic, algebraic equations, and possibly statistics or chemistry-related math for calculating concentrations. The exercises range from simple operations to more complex ones that incorporate formulas and algebraic manipulation.
To address these types of problems, students need to understand the mathematical concepts behind each exercise and apply the appropriate methods to find solutions. For example, when determining the mean in Solution 2.27, it involves adding a series of numbers and then dividing by the count of numbers, which is a fundamental concept in statistics. Other problems might require the use of algebra to solve for a variable.