From the given question
There are given that the equation:
[tex]z=ma-b[/tex]Now,
For finding the value of a, first, add b in both sides of the equation
So,
[tex]\begin{gathered} z=ma-b \\ z+b=ma-b+b \\ z+b=ma \end{gathered}[/tex]Then,
Divide by m on both sides the above equation
[tex]\begin{gathered} z+b=ma \\ \frac{z+b}{m}=\frac{ma}{m} \\ a=z+b \end{gathered}[/tex]Hence, the value of a is z + b.