To solve this system of equations, we will first solve for x in the first equation and then substitute that value into the second equation.

1) 0.8x + 2.1 = -6.7
Subtract 2.1 from both sides:
0.8x = -8.8
Divide by 0.8:
x = -11

Now, we substitute x = -11 into the second equation:

-0.5z - 1.5 = -7
-0.5z = -5.5
Divide by -0.5:
z = 11

Therefore, the solution to the system of equations is x = -11 and z = 11.