All this proof is essentially asking is to formally present and justify the work you'd normally to do solve for a. I'll go through the steps informally first, and then I'll justify them in the following part.
Our reason for the first line here would be
given; they provide the statement for us at the beginning.
To obtain the second line, we add 5 to both sides of the equation to cancel out the -5 term on the left side; here, we're using the
addition property of equality, which states that you adding the same number to both sides of an equation doesn't change its equality.
Finally, we
divide both sides by -6 to find that
. The property we use here is predictably called the division property of equality, and it states that dividing both sides of the equation by the same number doesn't change the equality. At this point, we've reached our conclusion and justified our steps, so we're done. Here's the completed proof:
Statement:
Reason: Given
Statement:
Reason: Addition property of equality
Statement:
Reason: Division property of equality