What does variability mean? Can you give an example?

I am talking about MATH here guys!!!

Lindsay used two points, (x, y; ) and (+2.82), to find the equation of the line, y = mx + b, that passes through the points. y2-y, first, she used the definition of slope and determined that the value of mis x, - . given this information, which expression must represent the value of b?

Combine like terms to make a simpler expression 3z+z

What is the ratio fraction form of 25: 9