Gegeven `z_1 = 5text(i)` en `z_2 = 12 + 7text(i)` .
Bereken `z_1 * z_2` .
Bereken `(z_1)/(z_2)` .
Bereken `(6 + 2z_1)*3z_2` .
Bereken `(6 + 2z_1)/(3z_2)` .