8z = 64
divide both sides with 8
8z ÷8 = 64÷8
therefore,
z = 8.
It would be the second answer. He starts with 2/3 cup, then take out 2 1/6 cup amounts, which make 2/6 cup. Since he's taking it out, you would subtract it from the original value. So you would get 2/3 cup minus 2/6 cup and to make the denominators equal you would multiply 2/3 cup by 2, so you would have 4/6 cup minus 2/6 cup which equals 2/6 cup.
The answer to life, the universe and everything is 42.