15x+6=10x+21 When finding x you must get x alone on one side. Start by
-10x -10x subtracting the equal number of the smallest x in the
5x+6=21 equation. Remember what you do to one side you must do to the
-6 -6 other side as well because both sides are equivalent to one
5x=15 another. Giving you no x value on one side. Then continue
/5 /5 getting x alone. Because it says +6 you must subtract six on
x=3 both sides. Which makes the 6 now equivalent to 0 so it is no longer apart of the equation. Then you must divide the value beside x by itself to make the x value equal 0. Never forget to do it to the other side as well. This gives you x=3.
I hope this helped you out.
I love doing these types of problems. :)