Goodness I am behind. We have gotten past combining like terms and using the distributive property so now we can concentrate on equations.
Equations are much like expressions except for 1 or 2 MAJOR things. Its all in the way they look. An equation has an equal sign (hint "equ" leads us to think equal) and also an equation gives a value after the equal sign. In an expression you do not have either of those things.
As we are beginning our work with equations we are starting with solutions and substitution. This is all mainly review because we worked with substitution when we were studying expressions. However now we are looking at both sides of the equal sign.
3 + x = 9 for x = 6 (this says that the value of x is 6, you must substitute it in to see if you get 9)
3 + 6 = 9
9 = 9 (yes, 6 is a solution because it makes the statement 3 + x = 9 TRUE).
4m = 24 for m = 7 (substitute the 7 for the m)
4 x 7 = 24
28 = 24 (since the 2 values are not the same, this means that 7 is not a solution)