It looks like this when you write it. Difference means subtract.
z - 11 = 35 To solve it, add 11 to both sides. That's called adding an additive inverse. It means you add something to both sides that has the opposite sign to the number that was present to start with. You have - 11. You want it to go to zero. So add + 11. The 11 on the left side is gone.
z - 11 + 11 = 35 + 11
z = 46