23=-3(21-z)+2(z-2)

Solution for 23=-3(21-z)+2(z-2) equation:

23=-3(21-z)+2(z-2)

We simplify the equation to the form, which is simple to understand 
23=-3(21-z)+2(z-2)

Reorder the terms in parentheses
23=+(-63+3z)+2*(z-2)

Remove unnecessary parentheses
+23=-63+3z+2+*(+z-2+)

Reorder the terms in parentheses
23=-63+3z+(+2z-4)

Remove unnecessary parentheses
+23=-63+3z+2z-4

We move all terms containing z to the left and all other terms to the right. 
-3z-2z=-63-4-23

We simplify left and right side of the equation. 
-5z=-90

We divide both sides of the equation by -5 to get z. 
z=18