Answer :
9/2= -10z-1/2(-10z+1)
multiply all terms by 2 to eliminate the fraction
9=-20z-(-10z+1)
remove ( ) distribute -1
9=-20z+ 10z-1
combine like terms
9= -10z -1
add 1 to both sides
10=-10z
divide by -10
-1=z
hope this helps