z = -b - a + 1
subtract 1
1z - 1 = -1b - 1a ( 1z is the same as z, same goes for b and a)
add -1b
1b - 1z - 1 = -1a
then we remove -1 by dividing it.
-1b -(-1z) + 1
Answer: -1b -(-1z) + 1 = A
A negative minus a negative is a positive, so the answer might as well be....
-1b + 1z + 1 = A
