The steps you take to solve an equation of this sort are informed by the Order of Operations. Look at what operations are performed on the variable when you evaluate this equation. They are
• x is divided by 2
• 5 is added to the quotient
To solve for x, you "undo" these operations in reverse order. To "undo" addition, you perform subtraction. Here, you (IV.) subtract 5 from both sides as the first step of your solution.
Then you undo the division by 2. To "undo" division, you perform multiplication. Here, you (I.) multiply both sides by 2 as the second step of your solution.
In summary, the order of steps you would take to solve this equation is
... IV
... I
_____
x/2 + 5 = 9
x/2 = 4 . . . . . . . . subtract 5
x = 8 . . . . . . . . . . multiply by 2
Note that in our description of the operation we performed, we simply say "subtract 5" because the properties of equality require that you do that to both sides of the equation.
