(Equation) a - 3 = -8
Explanation: If you're asked to solve for a in the equation a - 3 = -8, you want to try to get a by itself on one side of the equation.
If we take a look at the left side of our equation, a 3 is being subtracted from a so in order to get a by itself, we must add 3 to the left side of the equation. If we add 3 to the left side of the equation, we must also add 3 to the right side of the equation to keep our equation balanced.
On the left side of the equation, our -3 and +3 cancel out and we're left with a. On the right side of the equation, -8 + 3 simplifies to -5 so a = -5.
To check our answer, we can substitute -5 back in for a in the original equation and we get (-5) - 3 = -8. (-5) - 3 can be thought of as (-5) + (-3) and you can see that this is a true statement so our answer checks.