Recall that variables represent changing values. In this unit, you will work with
equations that contain two different
variables. What types of situations might be
modeled with equations containing two or
more variables? If the value of one variable
changes, must the value of the other variable
change for the equation to remain true? How
would the number of solutions for an
equation with two variables differ from the
number of solutions for an equation with only
one? Explain.