Answer:
19=7z-2z
Rewrite the problem to have the variable at the left
7z-2z=19
Subtract
5z=19
Divide the both side of the equation by 5.
5z/5=19/5
Cancel 5 from the numerator and the denominator and be left with "z".
z=19/5
To have your answer in mixed fraction
z=3 4/5)
To have your answer in decimal divide
z=3.8