According to legend, why did Nebuchadnezzar build the Hanging Gardens of Babylon? to provide protection from invaders to show the entire ancient world that he had restored Babylon to glory to serve as a monument to the goddess Ishtar to please his homesick wife

You start off with the coefficient (or number that stands alone) by doing the inverse operation, if it's being added you subtract it on both sides. Then, you do the inverse operation of the number with a variable such as multiplication or division. When doing that step you should be left with the variable and the equal sign with the final answer.