i think you made a typo. what hinted that to me is the last equation you typed. you had =64z^2 = -121. it makes no sense to have the = in front of the 64 like that. are you sure it shouldn't be a minus sign, as in a - ?
look at the book again, maybe you should have: 4x - 5 = 3(2x + 7) and -64z^2 = -121